Cannot delete timeline group from add-in: InternalValidationError

[kriomant]

I have add-in with command which does this:

    design = adsk.fusion.Design.cast(app.activeProduct)
    timeline = design.timeline

    for selection in ui.activeSelections:
        selectedEnt = selection.entity
        timelineObj = selectedEnt.timelineObject
        timelineObj.parentGroup.deleteMe(False)

Various checks are removed for brevity. Only one entity is selected, it's inside of timeline group, but I get

File "…/adsk/fusion.py", line 95662, in deleteMe

return _fusion.TimelineGroup_deleteMe(self, deleteGroupAndContents)

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

RuntimeError: 2 : InternalValidationError : res

[BrianEkins]

I tried to reproduce this by creating many sketches, grouping some, and then deleting the group using the API. It works OK for me. Maybe the type of objects in the group is causing the different behavior? 

[kriomant · Accepted solution]

Seems I nailed it: group must be collapsed for you to be able to delete it.