Block visibility change

This happens to me in the release candidate 2

I moved this to a new thread since it doesn’t really look like it has anything to do with display performance for blocks and I don’t want it to get lost. I can’t exactly tell what I’m seeing in the video. Is a block disappearing after being edited?

I can’t tell when will it happen or how to fix in V6. I just undo, save the file in V5 and do the change and come back to V6 again.

It usually happens in layer changes of objects and polysurface control point edits.