Solved
Elevator stolen by a klepto, can't replace it
My sim's birthday party included a kleptomaniac guest who was somehow able to steal the elevator off of the apartment. I can't place a new one due to "out of bounds" or "outside of owned property" er...
If you can revert back to an earlier save, you should do that. I don't think there's any other way to fix it.
This kind of thing happened when they introduced Eco Lifestyle and the Sharing is Caring NAP let sims steal apartment lobby items, like the trash chute which couldn't be replaced. I haven't heard of anything like that happening for years though. As far as I know, elevators aren't items on a klepto's allowed list of things to consider.
