Hi NightCabbage, I can't seem to reproduce the problem...

Please let me know if you find any steps that will trigger it.

Maybe you were running into the same bug that PaQ reported though, which was for selection undo.

There's a special kind of undo that is available temporarily when you do a selection or visibility change. Immediately after you change the selection or visibility of any objects, if you made a mistake you can do an undo to restore the previous selection or visibility state, but unlike other undo actions these ones do not get saved in the actual undo stack for multiple steps because it would be annoying to have to step through every single selection action that you did while trying to recover geometry.

- Michael