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.
This is the same behavior I see as well on 1.11.0 for Nintendo Switch and I think it's related to what I reported in MCPE-45469 . Do you notice this behavior from naturally spawning blazes? I'm thinking not, but really haven't had a chance to investigate yet.
This happens to me a lot but I've experienced a few different variants. If I save and exit below sea level (in a mine) upon loading, I'll be dead on the surface at ground level above where I saved. If water was above me at the surface, I will have drowned, if ground was above me. I will have fallen to my death.
Additionally, this death at game load issue is far more prominent when the game crashes during auto saves. Crashing while autosave happens very often when quickly crossing oceans in a boat. In this case, I spawn dead at the bottom of the ocean.
Nintendo switch
1.9
Infinite world
Single player
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.