If you had a problem with stairs since the update...
I've read other people are having this problem, are you and have you solved it? And weirdly enough for my household, it is only one set of stairs? The other two it appears, they are happy to go up ...
Bumping for updates? I've been sticking temporary ladders into my builds to work around the bug, but I hope I'll be able to use my lovely open stairs again soon...