"Ghost" Inventory

Last night while I was playing on my friend's world, I had a full inventory, when I got off (selected 'Save & Quit' then closed game) I think my inventory was not saved, as when I hopped on today, everything was wiped clean from my inventory.

Sadly, I know I can't get my stack of iron and 5 diamonds back no matter what, but PLEASE, make sure others do not lose their inventories from this bug.