Hey!
Could you please elaborate - is it working instantly for you (and I mean instantly) or do you notice a delay when you press “undo”?
It’s easy to check by watching the mixer undo history list. Preferably in a real-working scenario - a medium-sized project with some 3rd party plugins.
Because this delay is the problem, not the undo itself.
Earlier it was instant except when adding/removing plug-ins (which is understandable). But now I have delay even when undoing my eq moves in Fabfilter Pro-q.