Placing down my furniture from the household inventory onto the new empty house made my furniture disappear. Here are the details: I moved my house from one lot to another so they would be on a bigger lot. I put some of the furniture in my household inventory because I planned to buy the new house with the furniture and just wanted to bring along a couple of new pieces that I had recently bought for the family.
When I moved, I could not afford the house furnished even if I sold my furniture but for some reason I could buy it unfurnished and chose to keep my furniture so that is what I chose to do. All of my furniture was in my household inventory so I proceeded to put it all down in the empty house.
I would place down the couch and it would disappear. Then I would hit the undo button and it would appear again in the household inventory. Then when I set it down again, it would be okay and be there. I had to do this for every item in the house. It didn't seem to matter if I was placing the furniture in the same spot it was in before or a different spot, it still disappeared when first placed.
Now, here is something interesting. While doing this, I tried putting the plants in the ground outside that I had also saved so they would have their garden. When putting the plants on the ground they would also disappear and I would have to undo, then place them again and they would be there. BUT if I put them in the planter straight away, they would not disappear. Hope this helps.