Library Corruption/Deletion

This is the second time this has happened to me.  I try saving something to my library and it says my library is full.  Cool, I'll just delete some things.  So I do and I can't save anything else still.  So at that point it's whatever I'll just continue playing the game and come back later.  I eventually close the game and when I come back (since this is the second time), I have a pretty good idea of what to expect when I get a message along the lines of  "something happened to this application after it was closed" and "Corrupted data." So I of course check my saves and they're fine, great.  I check my library and it's nothing but Maxis.

This becomes frustrating when one it's happened before, and two, this means any save file that I retired or replaced, I no longer have those sims, houses, anything.  It's fine when I can go and reupload my sims and builds that already exist in game, but what about the sims I never got to add to my game? The builds I never got to finish? Sometimes I'll play with genetics for a couple and make their kids beforehand so they don't have outrageous looking children, or I'll make sims so my already existing sims can make friends, have relationships, etc., I'll make townies to add more to the game, and I'll save a build so that I can finish it some other time and overwrite the file for whatever extra story I wanna make.  Then of course the typical houses, venues, and things that can be searched up.  I can't search up what I hadn't published

No where can I find my library storage limit. I don't know when it's full and going to corrupt until it happens.  So I then have to take the time to hurry and save all my households across all my save files.  Favoriting things hardly works either.  I don't want to fill up my library, so my next solution would be to favorite things right?  Only a fraction of what I favorite ends up in my favorites.  When I was a new player I went on a favoriting spree, when I go to look through it and see what I wanna do with these sims and builds, I see not even half of what I thought I added.  Not in my library either.  So I learned early on to just save to my library, but now it seems I can't do that without an eventual repercussion.

I really hope this is just an awful bug and not an intended mechanic.  Not sure if it's because I deleted Maxis items.  I don't use or want those sims or builds in comparison to the things I saved, actually wanting them to be there.  I genuinely have no idea why this occurs besides me having a full library.