Start Remote Debugging remains stuck at "Attaching debugger..." for Python Web App after debugger tunnel is successfully established

[v-ruizh]

OS: Win 11 x64
Build Version: 20260811.1

Repro Steps:

1. Create a new Python Web App.
2. Deploy a Python application to the Web App.
3. Right-click the Python Web App and select "Start Remote Debugging".
4. Wait for the remote debugging session to start.

Expect:
The debugger should successfully attach and start a debugging session, or return a clear error message if the attach operation fails.

Actual:
The remote debugging operation never completes and remains stuck at "Attaching debugger..." indefinitely.
The Output window shows that the tunnel and proxy server are successfully established, but the debugger never attaches and no error message is displayed.

More Info:

1. The operation remained stuck at "Attaching debugger..." for over 20 minutes without successfully attaching the debugger, displaying an error message, or timing out.
2. This issue does not reproduce for a Node web app.