Forum Discussion
I've had this problem as well, I first noticed it after building a greenhouse as a separate building and installing a glass roof on the greenhouse. After doing so, I noticed in first person mode that the ceilings disappeared and I could see the upper floors.
After playing around a bit, I was able to resolve the issue entirely in my game by using the sledgehammer tool to delete the ceiling of my greenhouse before installing the roof. Installing the glass roof while the ceiling is in place automatically removes the ceiling (because otherwise what would be the point of the glass roof...), but getting rid of it before even putting on the roof resolved my issue with the missing ceilings in the rest of my house.
Not sure if this will help anyone else, but it does seem to have worked in my own game.
This is what happened to me too with the separate greenhouse. It caused a problem for me trying to do anything (add walls, create flooring, place roofing etc) on the second story of the main house. I found a workaround from another thread that said to use a normal roof (non-glass basically) while working on the upper stories, then add the glass roof last. That's worked for me so far, but I haven't had any Sims go into the house yet so I'm curious if the flooring/walls/objects will persist or become unusable because the ceiling (aka second floor) is being removed when placing the glass roof. 🤔