I'm not really a builder so not sure if I can help you with this.
Did you try posting in the official forum at thesims3.com ? Either tech forum or the creative corner would probably be best.
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You could also try moving your Sims to a different house just to see if they behave differently in another house. (you don't need to save or save under a different name). This will give you an indication if it's the house that is at fault or if something is wrong with the Sim/savegame.
I haven't tried moving them yet, but they seem to act normal outside of the house - anyway I'll try that as soon as I get home.
I haven't posted on the official forum yet, I actually haven't thought about that, I'll do that tonight, thanks!
You could try going into build/buy mode and opening the cheat bar (Ctrl+Shift+C) and then typing in 'moveobjects on' without the apostophy things ('). Then you can click on your sim, move it around and place it somewhere else.
Hope I could help 🙂
