Rigid bodies keep deactivating and I can't bring it back

I have done a handful of rigid body sims and seemingly randomly, they will switch from working to acting as if there are no rigid bodies in the scene.

It happened one time where it was working great, and all I changed was I switched from Evee to Cycles. Still worked, I changed the amount of samples in Cycles to less samples, and then the sim stopped running, and I couldn’t bring it back. I hit undo, still didn’t come back.

Surely this must be a series of bugs, right? If not, what can I do differently to be able to spend more time designing animations, and less time trying to figure out how to bring back my simulation? It took me 4 days to do something that should have taken a couple hours because I spent the vast majority of the time trying to bring back the work that was there before.

Maybe this part should be a separate post, but also, I have objects that when rolling on the floor object (cube) parts of the objects rolling will pernitrate the floor object. When I switched from convex hull to “mesh” then the whole object floated above the floor way to far up to look good. Is there a fix for that?