Doug Dunkle

This happens on the Nintendo switch as well.  Sometimes I lose items that I've recently moved around between chests or inventory, other times it duplicates the items.  I haven't been able to pin down the exact ordering, but it seems hit or miss as to whether items are lost or duplicated.

I can confirm (although I'm pretty sure I don't really count for the 'confirmation status') "Random frame drops (either to 30 or 0) when game is saving" and "Elytras able to outrun world loading (even with lowest settings on)" on 1.11.1.

I see the same thing with Librarians and their enchanted book trades on Nintendo Switch.  It doesn't matter the trade costs (10 emeralds + 1 book, or 39 emeralds + 1 book) it never consumes the book, just the emeralds, yet I get the enchanted book. 

I +1'd the vote on this.  I see the exact same issue.  There's no "snap-to" box for the items on the right of the trade arrow.