Okay so I've been playing the Sims 4 with some friends and we started noticing that things were gone, starting with our computers and TV, and eventually (through leaving and returning to the lot for various reasons) we noticed the lamps, sinks, and chairs were missing as well. It happens to random objects whenever I return to our lot. At first we thought it might be a feature we didn't know about but I couldn't find anything related to that. We checked our household inventory, each inventory of the Sims, and checked the logs for any robberies or something of the sort. We haven't lived there long enough to pay bills and I'm pretty sure the repo thing was replaced with turning off electricity and whatnot. It happened once I started editing the house, but not before.

More info:
I have CC (yes I turned it off and tried, it still happens)
It's an apartment
It's just furniture items, no clothes or hair or Sims
for some reason the expensive stuff disappeared first
No money is being added to the bank
Only non CC items vanish (so far)

I own City Living, Cats and Dogs, Get Together, Dine Out, Outdoor Retreat, and Bowling Night Stuff.

I'm not sure if I'm missing any info, but I looked and I couldn't find anything related to this that was already posted, or at least had a solution that worked. I don't have any mods other than Items and Clothing

Check the Apartment Traits. Do you have goblins? They might be stealing things.

This is bug with the current patch level, there really isn't much you can but avoid playing apartments until or if it ever get fixed.

i dont play apartments. but i did noticed in my attic creatrion of a french palace that in the rooftop i added some decoration, and from the get-go some parts of the decoration are missing. i am guessing the apartment boundaries with usage gets buggy and objects start to "fall trough the level" and no up to this day nobody has come up with a fix or a mod. dont play apartments my recommendation use the attics as community lots.

Hi! There is a similar open bug report on the EA forum.

the patch to fix this issue has been released. go to install it!