On the test server, I have seen one one or two instances, items disappear. Once a house and another a crafted item.
This seems to be extremely limited, and is probably an error in the emu code, but I have not found any information on it.
It seems VERY isolated and has not occurred for any player in Live Server yet.
If this happens to you:
Create a trouble ticket in the help desk outlining what the item was, how you acquired it, and any other information. An Admin or CSR will look into the item and possibly replace it for you. Again, this has NEVER happened on live and could have been soley from a "rubberband issue" in SWGEmu on the test server.