It does sound like a similar issue. It was in the basement so the floor disappeared along with the stairs.
However there were numerous sims on the lot that I was playing but all of the items have disappeared. They are not in any inventories. I'm most interested in recovering all of the lost collectibles.
Did you ever make a backup ?
Did you check the auto-backups to see if they still contain them:
http://sims4.crinrict.com/en/2014/09/save-games/#wiederherstellen
If they do, you could try uploading those houses to the gallery and re-placing them in your current game.
