diff --git a/changes.d/7035.fix.md b/changes.d/7035.fix.md
new file mode 100644
index 00000000000..dc25fc20560
--- /dev/null
+++ b/changes.d/7035.fix.md
@@ -0,0 +1 @@
+Fixed platform subshell expression evaluating more than once for tasks triggered in paused workflow.
diff --git a/cylc/flow/exceptions.py b/cylc/flow/exceptions.py
index ee215b47c9d..7e55c014756 100644
--- a/cylc/flow/exceptions.py
+++ b/cylc/flow/exceptions.py
@@ -184,13 +184,13 @@ class PlatformError(CylcError):
     def __init__(
         self,
         message: str,
-        platform_name: str,
+        platform_name: str | None,
         *,
-        ctx: 'Optional[SubFuncContext]' = None,
-        cmd: Union[str, Sequence[str], None] = None,
-        ret_code: Optional[int] = None,
-        out: Optional[str] = None,
-        err: Optional[str] = None
+        ctx: 'SubFuncContext | None' = None,
+        cmd: str | Sequence[str] | None = None,
+        ret_code: int | None = None,
+        out: str | None = None,
+        err: str | None = None
     ) -> None:
         self.msg = message
         self.platform_name = platform_name
diff --git a/cylc/flow/platforms.py b/cylc/flow/platforms.py
index 87f64292cba..aed340c0423 100644
--- a/cylc/flow/platforms.py
+++ b/cylc/flow/platforms.py
@@ -128,7 +128,7 @@ def get_platform(
 
     Returns:
         platform: A platform definition dictionary. Uses either
-            get_platform() or platform_name_from_job_info(), but to the
+            get_platform() or _platform_name_from_job_info(), but to the
             user these look the same. This will be None if the platform
             definition uses a subshell.
 
@@ -169,7 +169,7 @@ def get_platform(
     task_job_section = task_conf['job'] if 'job' in task_conf else {}
     task_remote_section = task_conf['remote'] if 'remote' in task_conf else {}
     return platform_from_name(
-        platform_name_from_job_info(
+        _platform_name_from_job_info(
             glbl_cfg().get(['platforms']),
             task_job_section,
             task_remote_section,
@@ -329,7 +329,7 @@ def get_platform_from_group(
         return HOST_SELECTION_METHODS[method](platform_names)
 
 
-def platform_name_from_job_info(
+def _platform_name_from_job_info(
     platforms: Union[dict, 'OrderedDictWithDefaults'],
     job: Dict[str, Any],
     remote: Dict[str, Any],
@@ -407,14 +407,14 @@ def platform_name_from_job_info(
         ... }
         >>> job = {'batch system': 'slurm'}
         >>> remote = {'host': 'localhost'}
-        >>> platform_name_from_job_info(platforms, job, remote)
+        >>> _platform_name_from_job_info(platforms, job, remote)
         'sugar'
         >>> remote = {}
-        >>> platform_name_from_job_info(platforms, job, remote)
+        >>> _platform_name_from_job_info(platforms, job, remote)
         'sugar'
         >>> remote ={'host': 'desktop92'}
         >>> job = {}
-        >>> platform_name_from_job_info(platforms, job, remote)
+        >>> _platform_name_from_job_info(platforms, job, remote)
         'desktop92'
     """
 
@@ -581,9 +581,9 @@ def fail_if_platform_and_host_conflict(
     if 'platform' in task_conf and task_conf['platform']:
         fail_items = [
             f'\n * [{section}]{key}'
-            for section, keys in FORBIDDEN_WITH_PLATFORM.items()
+            for section, settings in FORBIDDEN_WITH_PLATFORM.items()
             if section in task_conf
-            for key, _ in keys.items()
+            for key in settings.keys()
             if (
                 key in task_conf[section] and
                 task_conf[section][key] is not None
diff --git a/cylc/flow/scheduler.py b/cylc/flow/scheduler.py
index 8f2532558e0..d7197381336 100644
--- a/cylc/flow/scheduler.py
+++ b/cylc/flow/scheduler.py
@@ -1341,7 +1341,7 @@ def release_tasks_to_run(self) -> bool:
         """
         pre_prep_tasks: Set['TaskProxy'] = set()
         if (
-            self.stop_mode is None
+            not self.stop_mode
             and self.auto_restart_time is None
             and self.reload_pending is False
         ):
@@ -1350,36 +1350,29 @@ def release_tasks_to_run(self) -> bool:
                 pre_prep_tasks.update(self.pool.tasks_to_trigger_now)
                 self.pool.tasks_to_trigger_now = set()
 
-            if self.is_paused:
-                # finish processing preparing tasks
-                pre_prep_tasks.update({
-                    itask for itask in self.pool.get_tasks()
-                    if itask.waiting_on_job_prep
-                })
-            else:
+            if not self.is_paused:
                 # release queued tasks
                 pre_prep_tasks.update(self.pool.release_queued_tasks())
 
-        elif (
-            (
-                # Need to get preparing tasks to submit before auto restart
-                self.should_auto_restart_now()
-                and self.auto_restart_mode == AutoRestartMode.RESTART_NORMAL
-            ) or (
-                # Need to get preparing tasks to submit before reload
-                self.reload_pending
-            )
+        if (
+            # Manually triggered tasks will be preparing and should
+            # be submitted even if paused (unless workflow is stopping).
+            self.is_paused and not self.stop_mode
+        ) or (
+            # Need to get preparing tasks to submit before auto restart
+            self.should_auto_restart_now()
+            and self.auto_restart_mode == AutoRestartMode.RESTART_NORMAL
+        ) or (
+            # Need to get preparing tasks to submit before reload
+            self.reload_pending
         ):
-            # finish processing preparing tasks first
-            pre_prep_tasks = {
-                itask for itask in self.pool.get_tasks()
-                if itask.state(TASK_STATUS_PREPARING)
-            }
+            pre_prep_tasks.update({
+                itask
+                for itask in self.pool.get_tasks()
+                if itask.waiting_on_job_prep
+            })
 
         # Return, if no tasks to submit.
-        else:
-            return False
-
         if not pre_prep_tasks:
             return False
 
diff --git a/cylc/flow/task_job_mgr.py b/cylc/flow/task_job_mgr.py
index 47f0a17e7f5..996c5cb5014 100644
--- a/cylc/flow/task_job_mgr.py
+++ b/cylc/flow/task_job_mgr.py
@@ -56,7 +56,6 @@
     NoPlatformsError,
     PlatformError,
     PlatformLookupError,
-    WorkflowConfigError,
 )
 from cylc.flow.hostuserutil import (
     get_host,
@@ -70,6 +69,7 @@
 from cylc.flow.pathutil import get_remote_workflow_run_job_dir
 from cylc.flow.platforms import (
     FORBIDDEN_WITH_PLATFORM,
+    fail_if_platform_and_host_conflict,
     get_host_from_platform,
     get_install_target_from_platform,
     get_localhost_install_target,
@@ -1168,15 +1168,7 @@ def _prep_submit_task_job(
         # - host exists - eval host_n
         # remove at:
         #     Cylc8.x
-        if (
-            rtconfig['platform'] is not None and
-            rtconfig['remote']['host'] is not None
-        ):
-            raise WorkflowConfigError(
-                "A mixture of Cylc 7 (host) and Cylc 8 (platform) "
-                "logic should not be used. In this case for the task "
-                f"\"{itask.identity}\" the following are not compatible:\n"
-            )
+        fail_if_platform_and_host_conflict(rtconfig, itask.tdef.name)
 
         host_name, platform_name = None, None
         try:
@@ -1196,37 +1188,41 @@ def _prep_submit_task_job(
                 )
 
         except PlatformError as exc:
-            itask.waiting_on_job_prep = False
-            itask.summary['platforms_used'][itask.submit_num] = ''
-            # Retry delays, needed for the try_num
-            self._create_job_log_path(itask)
-            self._set_retry_timers(itask, rtconfig)
-            self._prep_submit_task_job_error(
-                itask, '(remote host select)', exc
-            )
+            self._prep_submit_task_job_platform_error(itask, rtconfig, exc)
             return False
         else:
-            # host/platform select not ready
             if host_name is None and platform_name is None:
+                # host/platform select not ready
                 return None
             elif (
                 host_name is None
                 and rtconfig['platform']
                 and rtconfig['platform'] != platform_name
             ):
-                LOG.debug(
+                msg = (
                     f"for task {itask.identity}: platform = "
-                    f"{rtconfig['platform']} evaluated as {platform_name}"
+                    f"{rtconfig['platform']} evaluated as '{platform_name}'"
                 )
-
+                if not platform_name:
+                    self._prep_submit_task_job_platform_error(
+                        itask, rtconfig, msg
+                    )
+                    return False
+                LOG.debug(msg)
             elif (
                 platform_name is None
                 and rtconfig['remote']['host'] != host_name
             ):
-                LOG.debug(
+                msg = (
                     f"[{itask}] host = "
-                    f"{rtconfig['remote']['host']} evaluated as {host_name}"
+                    f"{rtconfig['remote']['host']} evaluated as '{host_name}'"
                 )
+                if not host_name:
+                    self._prep_submit_task_job_platform_error(
+                        itask, rtconfig, msg
+                    )
+                    return False
+                LOG.debug(msg)
 
             try:
                 platform = cast(
@@ -1293,6 +1289,20 @@ def _prep_submit_task_job(
         itask.local_job_file_path = local_job_file_path
         return itask
 
+    def _prep_submit_task_job_platform_error(
+        self, itask: 'TaskProxy', rtconfig: dict, exc: Exception | str
+    ):
+        """Helper for self._prep_submit_task_job. On platform selection error.
+        """
+        itask.waiting_on_job_prep = False
+        itask.summary['platforms_used'][itask.submit_num] = ''
+        # Retry delays, needed for the try_num
+        self._create_job_log_path(itask)
+        self._set_retry_timers(itask, rtconfig)
+        self._prep_submit_task_job_error(
+            itask, '(remote host select)', exc
+        )
+
     def _prep_submit_task_job_error(
         self,
         itask: 'TaskProxy',
diff --git a/cylc/flow/task_pool.py b/cylc/flow/task_pool.py
index f9168106de7..4a566b1af51 100644
--- a/cylc/flow/task_pool.py
+++ b/cylc/flow/task_pool.py
@@ -900,8 +900,7 @@ def remove(self, itask: 'TaskProxy', reason: Optional[str] = None) -> None:
         except KeyError:
             pass
         else:
-            with suppress(KeyError):
-                self.tasks_to_trigger_now.remove(itask)
+            self.tasks_to_trigger_now.discard(itask)
             self.tasks_removed = True
             self.active_tasks_changed = True
             if not self.active_tasks[itask.point]:
@@ -1042,7 +1041,7 @@ def count_active_tasks(self):
 
         return active_task_counter, pre_prep_tasks
 
-    def release_queued_tasks(self):
+    def release_queued_tasks(self) -> set['TaskProxy']:
         """Return list of queue-released tasks awaiting job prep.
 
         Note:
@@ -1071,7 +1070,7 @@ def release_queued_tasks(self):
                 self.spawn_on_all_outputs(itask)
 
         # Note: released and pre_prep_tasks can overlap
-        return list(set(released + pre_prep_tasks))
+        return set(released + pre_prep_tasks)
 
     def get_min_point(self):
         """Return the minimum cycle point currently in the pool."""
diff --git a/cylc/flow/task_remote_mgr.py b/cylc/flow/task_remote_mgr.py
index d2a8a916097..45e21c32540 100644
--- a/cylc/flow/task_remote_mgr.py
+++ b/cylc/flow/task_remote_mgr.py
@@ -37,7 +37,6 @@
     Dict,
     List,
     NamedTuple,
-    Optional,
     Set,
     TYPE_CHECKING,
     Tuple,
@@ -120,8 +119,8 @@ def __init__(self, workflow, proc_pool, bad_hosts, db_mgr, server):
         self.server: WorkflowRuntimeServer = server
 
     def _subshell_eval(
-        self, eval_str: str, command_pattern: re.Pattern
-    ) -> Optional[str]:
+        self, eval_str: str | None, command_pattern: re.Pattern
+    ) -> str | None:
         """Evaluate a platform or host from a possible subshell string.
 
         Arguments:
@@ -175,7 +174,7 @@ def _subshell_eval(
     # BACK COMPAT: references to "host"
         # remove at:
         #     Cylc8.x
-    def eval_host(self, host_str: str) -> Optional[str]:
+    def eval_host(self, host_str: str | None) -> str | None:
         """Evaluate a host from a possible subshell string.
 
         Args:
@@ -191,7 +190,7 @@ def eval_host(self, host_str: str) -> Optional[str]:
             return 'localhost'
         return host
 
-    def eval_platform(self, platform_str: str) -> Optional[str]:
+    def eval_platform(self, platform_str: str | None) -> str | None:
         """Evaluate a platform from a possible subshell string.
 
         Args:
diff --git a/tests/functional/job-submission/19-platform_select.t b/tests/functional/job-submission/19-platform_select.t
index 6f6b6df9d2b..fb94ecb3676 100755
--- a/tests/functional/job-submission/19-platform_select.t
+++ b/tests/functional/job-submission/19-platform_select.t
@@ -17,7 +17,7 @@
 #-------------------------------------------------------------------------------
 # Test recovery of a failed host select command for a group of tasks.
 . "$(dirname "$0")/test_header"
-set_test_number 7
+set_test_number 8
 
 install_workflow "${TEST_NAME_BASE}"
 
@@ -29,24 +29,28 @@ logfile="${WORKFLOW_RUN_DIR}/log/scheduler/log"
 
 # Check that host = $(cmd) is correctly evaluated
 grep_ok \
-    "1/host_subshell/01:.* evaluated as improbable host name$" \
+    "1/host_subshell/01:.* evaluated as 'improbable host name'" \
     "${logfile}"
 grep_ok \
-    "1/localhost_subshell/01:.* evaluated as localhost$" \
+    "1/localhost_subshell/01:.* evaluated as 'localhost'" \
     "${logfile}"
 
 # Check that host = `cmd` is correctly evaluated
 grep_ok \
-    "1/host_subshell_backticks/01:.* evaluated as improbable host name$" \
+    "1/host_subshell_backticks/01:.* evaluated as 'improbable host name'" \
     "${logfile}"
 
 # Check that platform = $(cmd) correctly evaluated
 grep_ok \
-    "1/platform_subshell:.* evaluated as improbable platform name$" \
+    "1/platform_subshell:.* evaluated as 'improbable platform name'" \
     "${logfile}"
 
 grep_ok \
-    "1/platform_subshell_suffix:.* evaluated as prefix-middle-suffix$" \
+    "1/platform_subshell_empty:.* evaluated as ''" \
     "${logfile}"
 
-purge
+grep_ok \
+    "1/platform_subshell_suffix:.* evaluated as 'prefix-middle-suffix'" \
+    "${logfile}"
+
+# purge
diff --git a/tests/functional/job-submission/19-platform_select/flow.cylc b/tests/functional/job-submission/19-platform_select/flow.cylc
index 902eae68eb7..8a248ebe21e 100644
--- a/tests/functional/job-submission/19-platform_select/flow.cylc
+++ b/tests/functional/job-submission/19-platform_select/flow.cylc
@@ -17,6 +17,7 @@ purpose = """
             localhost_subshell
             platform_subshell:submit-fail?
             platform_no_subshell:submit-fail?
+            platform_subshell_empty:submit-fail?
             platform_subshell_suffix:submit-fail?
             host_subshell:submit-fail?
             host_subshell_backticks:submit-fail?
@@ -36,6 +37,9 @@ purpose = """
     [[platform_subshell]]
         platform = $(echo "improbable platform name")
 
+    [[platform_subshell_empty]]
+        platform = $(echo "")
+
     [[platform_subshell_suffix]]
         platform = prefix-$( echo middle )-suffix
 
diff --git a/tests/functional/job-submission/19-platform_select/reference.log b/tests/functional/job-submission/19-platform_select/reference.log
index 1b92c61a069..854550298a4 100644
--- a/tests/functional/job-submission/19-platform_select/reference.log
+++ b/tests/functional/job-submission/19-platform_select/reference.log
@@ -5,3 +5,4 @@
 1/host_subshell_backticks -triggered off [] in flow 1
 1/localhost_subshell -triggered off [] in flow 1
 1/platform_subshell_suffix -triggered off [] in flow 1
+1/platform_subshell_empty -triggered off [] in flow 1
diff --git a/tests/functional/platforms/04-host-to-platform-upgrade-fail-inherit.t b/tests/functional/platforms/04-host-to-platform-upgrade-fail-inherit.t
index 8812fefc0de..38b9eaee0bd 100644
--- a/tests/functional/platforms/04-host-to-platform-upgrade-fail-inherit.t
+++ b/tests/functional/platforms/04-host-to-platform-upgrade-fail-inherit.t
@@ -19,7 +19,7 @@
 # Child function not valid after inheritance.
 # Check for task failure at job-submit.
 . "$(dirname "$0")/test_header"
-set_test_number 3
+set_test_number 2
 
 create_test_global_config '' "
 # non-existent platform
@@ -29,16 +29,11 @@ create_test_global_config '' "
 
 install_workflow "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
 
-# Both of these cases should validate ok.
-run_ok "${TEST_NAME_BASE}-validate" \
-    cylc validate "${WORKFLOW_NAME}"
-
 # Run the workflow
 workflow_run_fail "${TEST_NAME_BASE}-run" \
-    cylc play --debug --no-detach "${WORKFLOW_NAME}"
+    cylc play --no-detach "${WORKFLOW_NAME}"
 
-# Grep for inherit-fail to fail later at submit time
-grep_ok "WorkflowConfigError:.*1/non-valid-child" \
+grep_ok "Task 'non-valid-child' has the following deprecated '\[runtime\]' setting(s)" \
     "${TEST_NAME_BASE}-run.stderr"
 
 purge
diff --git a/tests/functional/platforms/12-ping-pong/flow.cylc b/tests/functional/platforms/12-ping-pong/flow.cylc
index bc238486a1f..578092e5aa5 100644
--- a/tests/functional/platforms/12-ping-pong/flow.cylc
+++ b/tests/functional/platforms/12-ping-pong/flow.cylc
@@ -14,11 +14,9 @@
         platform = $(cat ${CYLC_WORKFLOW_RUN_DIR}/pretend-hall-info)
 
     [[toggler]]
+        # Toggle the platform between localhost and the remote host
+        # using the content of a file, ${CYLC_WORKFLOW_RUN_DIR}/pretend-hall-info.
         script = """
-            # Toggle the platform between localhost and the remote host
-            # using the content of a file, ${CYLC_WORKFLOW_RUN_DIR}/pretend-hall-info.
-            # between localhost and the remote.
-
             if (( $CYLC_TASK_CYCLE_POINT % 2 == 1 )); then
                 echo ${REMOTE_PLATFORM} > ${CYLC_WORKFLOW_RUN_DIR}/pretend-hall-info
                 cylc message -- "changing platform to ${REMOTE_PLATFORM}"
diff --git a/tests/functional/platforms/14-trigger-paused-subshell.t b/tests/functional/platforms/14-trigger-paused-subshell.t
new file mode 100644
index 00000000000..dc2d5e57415
--- /dev/null
+++ b/tests/functional/platforms/14-trigger-paused-subshell.t
@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+# THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
+# Copyright (C) NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Triggering a task with a subshell platform setting while the workflow is
+# paused should only evaluate the subshell once.
+# Here we have a subshell command that alternates between two platforms on each
+# call, to check the platform does not change during a manual trigger.
+# https://github.com/cylc/cylc-flow/issues/6994
+
+export REQUIRE_PLATFORM='loc:remote'
+
+. "$(dirname "$0")/test_header"
+set_test_number 11
+
+install_workflow "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
+
+local_host_name=$(hostname)
+remote_host_name=$(cylc config -i "[platforms][${CYLC_TEST_PLATFORM}]hosts")
+remote_host_name=$(ssh -oStrictHostKeyChecking=no "$remote_host_name" hostname)
+workflow_log="${WORKFLOW_RUN_DIR}/log/scheduler/log"
+# shellcheck disable=SC2034  # LOG_SCAN_GREP_OPTS is not unused
+LOG_SCAN_GREP_OPTS="-E"
+
+run_ok "${TEST_NAME_BASE}-validate" cylc validate "${WORKFLOW_NAME}"
+cylc play "${WORKFLOW_NAME}" --pause
+poll_grep_workflow_log "1/foo:waiting"
+
+cylc trigger "${WORKFLOW_NAME}//1/foo"
+
+log_scan "log-grep-01" "$workflow_log" 10 2 \
+    "\[1/foo/01:preparing\] submitted to localhost" \
+    "\[1/foo/01:.*\] \(received\)${local_host_name}" \
+    "\[1/foo/01:.*\] => succeeded"
+
+cylc trigger "${WORKFLOW_NAME}//1/foo"
+
+log_scan "log-grep-02" "$workflow_log" 10 2 \
+    "\[1/foo/02:preparing\] submitted to ${CYLC_TEST_PLATFORM}" \
+    "\[1/foo/02:.*\] \((received|polled)\)${remote_host_name}" \
+    "\[1/foo/02:.*\] => succeeded"
+
+cylc trigger "${WORKFLOW_NAME}//1/foo"
+
+log_scan "log-grep-03" "$workflow_log" 10 2 \
+    "\[1/foo/03:preparing\] submitted to localhost" \
+    "\[1/foo/03:.*\] \(received\)${local_host_name}" \
+    "\[1/foo/03:.*\] => succeeded"
+
+cylc stop "${WORKFLOW_NAME}" --now --now
+
+# Check DB as well:
+sqlite3 "${WORKFLOW_RUN_DIR}/.service/db" \
+    "SELECT submit_num, platform_name FROM task_jobs" > task_jobs.out
+cmp_ok task_jobs.out <<__EOF__
+1|localhost
+2|${CYLC_TEST_PLATFORM}
+3|localhost
+__EOF__
+
+poll_workflow_stopped
+purge
diff --git a/tests/functional/platforms/14-trigger-paused-subshell/flow.cylc b/tests/functional/platforms/14-trigger-paused-subshell/flow.cylc
new file mode 100644
index 00000000000..0993ec7b41e
--- /dev/null
+++ b/tests/functional/platforms/14-trigger-paused-subshell/flow.cylc
@@ -0,0 +1,13 @@
+#!jinja2
+[scheduling]
+    [[graph]]
+        R1 = foo:never  # Allows triggering repeatedly without workflow shutting down
+
+[runtime]
+    [[foo]]
+        platform = $("${CYLC_WORKFLOW_RUN_DIR}/toggle_platform.sh" {{ CYLC_TEST_PLATFORM }})
+        # Check what host we have truly run on:
+        script = cylc message -- "$(hostname)"
+
+        [[[outputs]]]
+            never = gonna_give_u_up
diff --git a/tests/functional/platforms/14-trigger-paused-subshell/toggle_platform.sh b/tests/functional/platforms/14-trigger-paused-subshell/toggle_platform.sh
new file mode 100755
index 00000000000..8910d6bc251
--- /dev/null
+++ b/tests/functional/platforms/14-trigger-paused-subshell/toggle_platform.sh
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+# THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
+# Copyright (C) NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Script that outputs the current platform written in the hall file and changes
+# it to the other one. This ensures the platform subshell result will alternate
+# each time it is called.
+
+remote_platform=$1
+hall_file="${CYLC_WORKFLOW_RUN_DIR}/pretend_hall_info"
+
+if [[ ! -f "${hall_file}" ]]; then
+    current=localhost
+else
+    current=$(cat "$hall_file")
+fi
+
+echo "$current"
+
+if [[ "$current" == localhost ]]; then
+    echo "$remote_platform" > "$hall_file"
+else
+    echo localhost > "$hall_file"
+fi
diff --git a/tests/integration/conftest.py b/tests/integration/conftest.py
index 342bb1d58d0..228ceed49ab 100644
--- a/tests/integration/conftest.py
+++ b/tests/integration/conftest.py
@@ -627,7 +627,10 @@ async def _complete(
 
     """
     if schd.is_paused and not allow_paused:
-        raise Exception("Cannot wait for completion of a paused scheduler")
+        raise Exception(
+            "You are waiting for a paused scheduler - if this is intended "
+            "then use `complete(..., allow_paused=True)`"
+        )
 
     start_time = time()
 
diff --git a/tests/integration/test_force_trigger.py b/tests/integration/test_force_trigger.py
index 1ad169986e0..1e60074b88a 100644
--- a/tests/integration/test_force_trigger.py
+++ b/tests/integration/test_force_trigger.py
@@ -16,22 +16,17 @@
 
 import asyncio
 import logging
-import sys
 from typing import (
     Any as Fixture,
-    Callable
+    Callable,
 )
 
-if sys.version_info[:2] >= (3, 11):
-    from asyncio import timeout as async_timeout
-else:
-    from async_timeout import timeout as async_timeout
 import pytest
 
 from cylc.flow.commands import (
     force_trigger_tasks,
-    reload_workflow,
     hold,
+    reload_workflow,
     resume,
     run_cmd,
     set_prereqs_and_outputs,
@@ -47,7 +42,17 @@
 )
 
 
-async def test_trigger_workflow_paused(
+async def test_workflow_paused_simple(
+    one_conf, flow, scheduler, run, complete
+):
+    """It should run triggered tasks even if the workflow is paused."""
+    schd: Scheduler = scheduler(flow(one_conf), paused_start=True)
+    async with run(schd):
+        await run_cmd(force_trigger_tasks(schd, ['1/one'], ['1']))
+        await complete(schd, '1/one', allow_paused=True, timeout=1)
+
+
+async def test_workflow_paused_queues(
     flow: 'Fixture',
     scheduler: 'Fixture',
     start: 'Fixture',
@@ -116,7 +121,8 @@ async def test_trigger_workflow_paused(
 
 
 async def test_trigger_group_whilst_paused(flow, scheduler, run, complete):
-    """Only group start tasks should run whilst the scheduler is paused.
+    """Only group start tasks should run if the group is triggered whilst
+    the scheduler is paused.
 
     Group start tasks have only off-group dependencies.
 
@@ -124,14 +130,8 @@ async def test_trigger_group_whilst_paused(flow, scheduler, run, complete):
     prerequisites are satisfied once the workflow is resumed.
 
     """
-    id_ = flow(
-        {
-            'scheduling': {
-                'graph': {'R1': 'a => b => c => d'},
-            },
-        }
-    )
-    schd = scheduler(id_)
+    id_ = flow('a => b => c => d')
+    schd = scheduler(id_, paused_start=True)
     async with run(schd):
         # trigger the chain
         await run_cmd(force_trigger_tasks(schd, ['1/a'], []))
@@ -673,7 +673,7 @@ async def test_trigger_with_sequential_task(flow, scheduler, run, log_filter):
     schd = scheduler(id_, paused_start=False)
     async with run(schd):
         # wait for 2/foo:failed
-        async with async_timeout(5):
+        async with asyncio.timeout(5):
             while True:
                 itask = schd.pool._get_task_by_id('2/foo')
                 if itask and itask.state.outputs.is_message_complete('failed'):
@@ -688,33 +688,13 @@ async def test_trigger_with_sequential_task(flow, scheduler, run, log_filter):
         )
 
         # it should re-run
-        async with async_timeout(5):
+        async with asyncio.timeout(5):
             while True:
                 if log_filter(contains='[2/foo/02:running] (received)failed'):
                     break
                 await asyncio.sleep(0)
 
 
-async def test_trigger_whilst_paused_preparing(one, run, complete):
-    """It should run "preparing" tasks even if the workflow is paused.
-
-    Remote init leaves tasks as preparing for a while. These must still be
-    pushed through to running, even if triggered while the workflow is paused.
-
-    See https://github.com/cylc/cylc-flow/pull/6768
-
-    """
-    async with run(one):
-        await run_cmd(
-            force_trigger_tasks(
-                one, [one.pool.get_tasks()[0].tokens.relative_id], ['1']
-            )
-        )
-
-        # 1/a should run even though the workflow is paused.
-        await complete(one, '1/one', allow_paused=True, timeout=1)
-
-
 async def test_trigger_with_task_selector(flow, scheduler, start, monkeypatch):
     """Test task matching with the trigger command.
 
diff --git a/tests/integration/test_reload.py b/tests/integration/test_reload.py
index 86ef0c72490..59d2fc0eacf 100644
--- a/tests/integration/test_reload.py
+++ b/tests/integration/test_reload.py
@@ -36,7 +36,6 @@ async def test_reload_waits_for_pending_tasks(
     scheduler,
     start,
     monkeypatch,
-    capture_submission,
     log_scan,
 ):
     """Reload should flush out preparing tasks and pause the workflow.
@@ -47,9 +46,11 @@ async def test_reload_waits_for_pending_tasks(
 
     See https://github.com/cylc/cylc-flow/issues/5107
     """
+    # speed up the test:
+    monkeypatch.setattr('cylc.flow.scheduler.sleep', lambda *_: None)
     # a simple workflow with a single task
     id_ = flow('foo')
-    schd = scheduler(id_, paused_start=False)
+    schd: Scheduler = scheduler(id_, paused_start=False)
 
     # we will artificially push the task through these states
     state_seq = [
@@ -63,26 +64,26 @@ async def test_reload_waits_for_pending_tasks(
 
     # start the scheduler
     async with start(schd) as log:
-        # disable submission events to prevent anything from actually running
-        capture_submission(schd)
+        foo = schd.pool.get_tasks()[0]
 
         # set the task to go through some state changes
-        def change_state(_=0):
-            with suppress(IndexError):
+        def submit_task_jobs(*a, **k):
+            try:
                 foo.state_reset(state_seq.pop(0))
+            except IndexError:
+                foo.waiting_on_job_prep = False
+            return [foo]
+
         monkeypatch.setattr(
-            'cylc.flow.scheduler.sleep',
-            change_state
+            schd.task_job_mgr, 'submit_task_jobs', submit_task_jobs
         )
 
         # the task should start as waiting
-        tasks = schd.pool.get_tasks()
-        assert len(tasks) == 1
-        foo = tasks[0]
-        assert tasks[0].state(TASK_STATUS_WAITING)
+        assert foo.state(TASK_STATUS_WAITING)
 
         # put the task into the preparing state
-        change_state()
+        schd.release_tasks_to_run()
+        assert foo.state(TASK_STATUS_PREPARING)
 
         # reload the workflow
         await commands.run_cmd(commands.reload_workflow(schd))
@@ -96,12 +97,11 @@ def change_state(_=0):
             [
                 # the task should have entered the preparing state before the
                 # reload was requested
-                '[1/foo:waiting(queued)] => preparing(queued)',
+                '[1/foo:waiting] => preparing',
                 # the reload should have put the workflow into the paused state
                 'Pausing the workflow: Reloading workflow',
                 # reload should have waited for the task to submit
-                '[1/foo/00:preparing(queued)]'
-                ' => submitted(queued)',
+                '[1/foo/00:preparing] => submitted',
                 # before then reloading the workflow config
                 'Reloading the workflow definition.',
                 # post-reload the workflow should have been resumed
diff --git a/tests/unit/test_platforms.py b/tests/unit/test_platforms.py
index c32b4b5e717..ef594acfab5 100644
--- a/tests/unit/test_platforms.py
+++ b/tests/unit/test_platforms.py
@@ -16,23 +16,31 @@
 #
 # Tests for the platform lookup.
 
+from typing import (
+    Any,
+    Dict,
+    List,
+    Optional,
+    Type,
+)
+
 import pytest
-from typing import Any, Dict, List, Optional, Type
 
+from cylc.flow.exceptions import (
+    GlobalConfigError,
+    PlatformLookupError,
+)
 from cylc.flow.parsec.OrderedDict import OrderedDictWithDefaults
 from cylc.flow.platforms import (
+    _platform_name_from_job_info,
+    _validate_single_host,
+    generic_items_match,
+    get_install_target_from_platform,
+    get_install_target_to_platforms_map,
     get_platform,
     get_platform_deprecated_settings,
     is_platform_definition_subshell,
-    platform_from_name, platform_name_from_job_info,
-    get_install_target_from_platform,
-    get_install_target_to_platforms_map,
-    generic_items_match,
-    _validate_single_host
-)
-from cylc.flow.exceptions import (
-    PlatformLookupError,
-    GlobalConfigError
+    platform_from_name,
 )
 from cylc.flow.run_modes import JOBLESS_MODES
 
@@ -270,11 +278,11 @@ def test_similar_but_not_exact_match():
     ]
 )
 def test_platform_name_from_job_info_basic(job, remote, returns):
-    assert platform_name_from_job_info(PLATFORMS, job, remote) == returns
+    assert _platform_name_from_job_info(PLATFORMS, job, remote) == returns
 
 
 def test_platform_name_from_job_info_evaluated_hostname():
-    result = platform_name_from_job_info(
+    result = _platform_name_from_job_info(
         PLATFORMS,
         {'batch system': 'background'},
         {'host': '$(cat tiddles)'},
@@ -294,7 +302,7 @@ def test_platform_name_from_job_info_ordered_dict_comparison():
     platform.defaults_['Made up key'] = {}
     platform.update(PLATFORMS['hpc1-bg'])
     platforms = {'hpc1-bg': platform, 'dobbie': PLATFORMS['sugar']}
-    assert platform_name_from_job_info(platforms, job, remote) == 'hpc1-bg'
+    assert _platform_name_from_job_info(platforms, job, remote) == 'hpc1-bg'
 
 
 # Cases where the error ought to be raised because no matching platform should
@@ -321,7 +329,7 @@ def test_platform_name_from_job_info_ordered_dict_comparison():
 )
 def test_reverse_PlatformLookupError(job, remote):
     with pytest.raises(PlatformLookupError):
-        platform_name_from_job_info(PLATFORMS, job, remote)
+        _platform_name_from_job_info(PLATFORMS, job, remote)
 
 
 # An example of a global config with two Spice systems available
@@ -359,7 +367,7 @@ def test_platform_name_from_job_info_two_spices(
         },
 
     }
-    assert platform_name_from_job_info(platforms, job, remote) == returns
+    assert _platform_name_from_job_info(platforms, job, remote) == returns
 
 
 # An example of two platforms with the same hosts and job runner settings
@@ -406,7 +414,7 @@ def test_platform_name_from_job_info_similar_platforms(
             'job runner': 'background'
         },
     }
-    assert platform_name_from_job_info(platforms, job, remote) == returns
+    assert _platform_name_from_job_info(platforms, job, remote) == returns
 
 
 # -----------------------------------------------------------------------------