Hi Schmidi
I have looked at your file
At first I thought it was the way you had used walls to make your model (you have 7 walls in places that could just use one new composite). But this was not the problem
I noticed that the interactive scheduler would pickup the zone, but the window itself would not.
So I scripted an ArchiCAD window (so I knew it was not a 4D Library issue) to show the zone in plan - and it would not show the zone unless the walls and zone were at zero to the project
I then changed the wall projection to 'symbolic' and the zones started to work
The fix is to set all your walls to 'Symbolic' in 'Floor plan and section..' within the window and doors settings.
This is definite bug. I will report it to GS.