We've had similar issues .. but with as many items as we move in a day, it's possible to make mistakes (Did I move that stuff? Did I have 28 tracking devices here or only 27?) so we've dismissed it as human error ... on the other hand, we've had people swear up and down items aren't in a silo, and someone else goes and looks .. and there they are.
I've heard other people mention disappearing items, but nobody seems to really be sure ...
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When all its work is done, the lie shall rot; The truth is great, and shall prevail,
When none cares whether it prevail or not. - Coventry Patmore