v56 Undo does not work properly

I’ve found Undo to be erratic since I started using the Beta versions. It’s still very unstable. After making some Audio marker adjustments and changing from Audio Marker to Duration on some images, I wanted to go back to the prior adjustment. Undo moved my Audio track and changed every photo to Duration from Audio Marker. In fact Slides revert to Duration without any apparent logic that I can see, but that’s a slightly different problem.