Ideas
No, sadly; I did try that, and the Repair option - I can download what I like from the Gallery to my Library, but almost nothing will save to My Library from my games :(
MichyCoe79 ...I'm so sorry! Do you have the issue if you close the game and remove (and save) your entire 'The Sims 4' folder (Documents > Electronic Arts > The Sims 4) (just save it in a safe place on your computer or a thumb drive since it has all of the stuff you have worked on in it)... Then you can re-start the game and it will create a brand new The Sims 4 folder in that location... If you do that and open your game so that you have a brand new save you're starting, and by not adding anything to that new save but just going into a lot and trying to save a room and a lot from it into your library, does this still happen then?