Missing furniture and sim need to rent again

I've had this problem two or three times in 3 months. My sim lives in an apartment, goes too the neighborhood, comes back and most of the furniture is missing (everything without kitchen and batchroom) and they need to rent again. I didn't save the game but it looks like the game somehow saves by itself because it's the same when i load the family. When i change to the other family who also live in the apartment it's the same problem. I have Ultimate Collection, don't use CC or mods. Also they still use bed and easel??????