Invisible Objects (Again)

I've searched and found some pages about Invisible Objects being in the way, but my situation is a bit different. I know where the objects came from, and I want them back. My Sims just came back from Egypt and analyzed their collectables. I've got the best on display. I replaced the Old Egyptian Statue of Anubis with a $5,000 Ancient one. The hand moving it didn't seem to let go. When it did, the object disappeared. The same happened to a $1,500 Canopic Jar. These were very good relics. They seem to be on the shelf, since I can't put anything in that spot, but they seem to be invisible and I cannot grab them, either in live mode or build mode. How do I get these back?

Edit/Update
I quit and rebooted the computer. I just tried to replace the other Canopic Jar that I managed to keep, and it just disappeared. Now, how do I stop things from disappearing?