Can't save sims/house to my library.

@Maria_S_Avila  Please try saving a different house and a different set of sims to the library and see whether it works.  If it does, try saving your sims one at a time, and the house one room at a time, to see if there's a specific sim or room that's causing the problem.  Let me know what you find.

If nothing saves to the library at all, please go into Documents > Electronic Arts > The Sims 4, and move the Tray folder to the desktop.  Then try again to save something.  This will temporarily hide all your already-saved items, but the files themselves will still be intact in the folder you've moved and can be restored later.