"can't place room due to fixed object"

I was moving a sim in Evergreen Harbor. I moved the sim in with a bulldozed room so nothing should be there. Then, I downloaded a room from the gallery to place it on the lot, but it kept saying that it cant place it due to fixed object. I have no idea what object it would be especially since I bulldozed everything. So, I had to move my Sim somewhere else cause nothing was working.

It didn't work when I was editing on world map either.