Purchased books in bookshelves, pet toys and kid toys in toy boxes disappear

HelloNennaRC​  Do you use mods/cc? Does your sim’s personal inventory empty also?

NennaRC​  Yep, that can happen.  It's not a bug, just the way the game works.  Containers such as bookshelves, and toy boxes work differently depending on where they are in a residential rental.  If you place something in any type of container that is located in a shared space, it will usually disappear when you leave and return to the lot.  What you have to do is place a container in each apartment and store whatever it is there instead of using a container in shared space.  Then when you access the container that is in shared space, you will see the contents of the one in the apartment of the sim you are playing.   All containers work this way.  That includes toy boxes, bookshelves, fridges, and any other object that allows you to store anything in them like flower and EBN cure workstations and a few other things.

Hope this helps.

I do indeed have all bookshelves and toyboxes in each apartment but books and toys still disappear. I don't have any bookshelves or toyboxes in shared areas. I have never had them in shared spaces either. They were placed in each apartment from start when I built the house.

NennaRC​  Toys and books will go missing is if you have sims with certain traits that visit the household and "steal" things.  Klepo traited sims could do it but generally don't steal things like that though (they'd steal the entire bookcase or toy box, not the contents).  Childish sims will play with toys and not put them away or if they do, they put them in their own inventory or carry them out of the apartment.   Books can end up in chest containers if the chest container is closer than a bookcase or if you've placed one of the small book group bookshelves on a surface where sims seem to get a route block when putting books away.  Then the sims go into the sim inventory of the sim trying to put them away so if the sim is a visitor, the book disappears from the lot.  If you have a visitor sim reading or playing with a toy when you save and quit, the books and toys can end up in the sim's inventory when you reload.  The sim may or may not pull the item out and continue using it.  If they don't then the item is gone.

Hope this helps.

It’s not about one or another book/toy getting stolen. When I have built and furnished a house and moved in a household I usually fill toyboxes and bookshelves with almost all available books and toys by letting them buy them. The toys and books are in there as long as I play the game but after quitting the game and starting again later, bookshelves and toyboxes are empty and this happens on residential rental lots, not normal residential lots. As mentioned, these boxes and shelves are not placed in shared spaces. The items are not stolen, every item disappears. My sims don’t read every book in my filled bookshelves and have trouble putting them back or place them elsewhere. There are too many books and toys for that to empty all.