I've had the same problem. When I harvested soy beans in the new world they didn't show up in my inventory at all. My sims guitar disappeared from the inventory. A laptop disappeared from the lot, only to show up in the inventory, but only when on the community space lot. When traveling back it wasn't in the inventory again. Only to show up on the table again maybe a sim week later. A candle my sim made kept appearing in the inventory again and again after being sold on the selling table.
I have all packs except my first pet, spooky stuff and moschino stuff. I play with mccc and haven't bothered to remove it since I've read about people having the same problem in their vanilla games.
