Can't save sims/house to my library.

@Maria_S_Avila  You could try saving the houses one room at a time instead.  It's possible that only one room, or one item in one room, is bugged, and finding out what it is might save you a lot of time otherwise spent rebuilding.

If you do find an affected room, try deleting the objects inside and see whether it helps.  If it does, you can quit without saving and reload, this time deleting only some objects and testing until you find the problem.  It could be as simple as an empty plate from a custom recipe hidden on a shelf or half wall somewhere.