Stairs again...

The removing of the ceiling downstairs is anyway a major part of the issue often, since it decides not always to show the floor, but the ceiling of the floor below :)

edit: I actually went ahead and tried it:
1) draw a room downstairs and remove the ceiling, remove walls and put stairs
2) draw balcony and remove floor, remove part where stairs will be
3) put stairs (I had to add a room on the next floor to help me place them since I was missing the ceiling lol) I did remove that room afterwards

I think because of the fence and the stairs surrounding the entire room, this one is not as glitchy, I tried it, it didn't revert to original state when restarting the game.

https://i.imgur.com/mauBVkW.png