Mission control shrinks all open windows to nothing (2018 MacBook Pro running 10.15.7)

When I enter Mission control all the open windows shrink to nothing, and I see an empty desktop. Here is a 'hack' fix: I opened Mission Control Preference panel and checked the "group windows by app" box. Now the open wounds sort nicely into app specific piles that do not shrink to nothing. I saw another post that suggested the behavior may be triggered by having specific apps open, but I have not tested this, although I do run 3rd party non-app store apps like Matlab and COMSOL, and other sciences stuff.