[GALLERY] 'Timed Out' error when saving lot to Library/Gallery

I'm having the same issue when trying to save lots and rooms to my library (I'm on PC). Since some patch last autumn, I'm getting an error message almost every time I want to save a build, and sometimes it works after several tries, but often it won't work at all. The January 13th Update just changed the wording of the error message for me, but it occurs just as often. I've tried basically all of the aboved mentioned steps and others as well (taking out all my mods, repairing the game, deleting the cache folder, removing tray and save files temporarily, having the game create a fresh Sims 4 folder etc.), but nothing helps. I had the error occur with more cluttered lots as well as with simple empty shells, so it's apparently not about the file size. My internet connection is stable, but I also don't see why it would be required to just save stuff to my own library? Uploading to the gallery does work fine for me, it's just saving stuff to the library that won't.