I've tried different stairways (going both up and down) and using debug mode, but all of my characters are stuck on their respective floors (10, 12, 11).
Unfortunately, we tried to cover all savegames in the patch but we ended up more with 95% of them working correctly. It unfortunately sounds like yours aren't going to work, sorry. This was due to needing to rewrite the way saves are handled so that it would be better in the long run.