I managed to get stuck in block editing mode – basically the same issue as this old thread, except in Mac Rhino 8.29.26063.11002. This happened by undoing / redoing across block edit sessions, but unfortunately I can’t remember the exact sequence.
After closing and reopening the attached file, I find the block I was editing has been exploded, and all other geometry is locked.
In this case I can fix it manually, this is just to point out that the issue is back / didn’t go away…
MiniPlough.3dm (3.7 MB)