I have buttons with a command binding that works functional perfect, however depending on stuff I just can't figure out the visibility (grayed out) doesn't always gets applied. The button correctly can't be clicked and mouse over... works as if disabled but the style just doesn't get applied at times.

I have a large menu with many grids, sub grids and stack panels. I placed (for debugging) exact copies of same button in xaml in many different places and some works and some don't. I can see no pattern. Also after "can execute" has run a few times which works and which doesn't can change.

Scattered visibility binding seem to play a role but I see no pattern here either, some internal order gets changed.

I don't have time to repro this in an example project now, but just placing buttons with commands in different places in a complex and nested menu should probably reproduce it.