All items disappear

Any time I leave the lot, all items in the home and anything in Sims' inventories are deleted. All food from the fridge, all the books on the shelves, all of the pictures in frames, all of the artwork Sims made, toys from the dogs' toy box, and the kids' toy box, all of the pictures/harvestables/homework in inventories, and any in-progress artwork or books. And I don't get any money back from these items, so I'm wasting money replacing them just to forget about the bug and leave, and they all disappear again. Very frustrating.