Alembic export settings ignored until UI dialog opened manually

[mheberlein]

Hi there, the example https://github.com/PluginCafe/cinema4d_py_sdk_extended/blob/master/scripts/03_application_development/files_media/export_alembic_r14.py is great but a bug that "should have been fixed with version 18.030" seems to have come back:

• restart Cinema4D
• create multiple objects in scene
• select one object
• run example code
• all objects are exported, "Selection Only" is ignored
• open Alembic export settings dialog
• close the dialog without any changes
• run example code again
• only the selected object is exported, "Selection Only" applied correctly now