BigSur - MissionControl and Desktop preview

BTT 3.510
Big Sur 11.0.1
MBP 15" 2016

The function Mission Control show desktop preview will work some of the time but not all the time.
This happens with all triggers: Keyboard, Trackpad or Mouse center button

All the while it works fine on Catalina

It seems to work well here, but maybe it is a timing issue if the cpu is busy.

I'll have a deeper look.