Why your items disappear when duping.

So if you opened this thread, you might be wondering "Why do my items disappear every time I try to dupe?"
Well, the answers are logical, so you should read over this and try NOT to let the following things happen.

1. GoogleApp. Sometimes, although very rare, when receiving duped items from any client on a browser, the items can disappear out of nowhere. This has happened to me and a friend. Needs a little confirmation, but this is what I have read is the problem and it only happens on browsers.

2. Refilling your vault. When you refill your vault, be COMPLETELY SURE that you do NOT have anyone waiting to get into the vault. This can and will delete your items.

If you know of any more cases in which items might disappear, please tell me so I can add it to this post. These are the two most common ones.