Whenever you pick up an item with inventory opened (or pick item from inventory), it is put into special slot which follows your cursor. If you die, click on dead body to recover your items and put anything in that cursor slot in the meanwhile, this item will be forever lost after body is picked up.
I dont know if it occurs always or just for me. I died in the middle of monster pack, logged out and in to recover body in town. However it didnt wear-up due to str reqs (enigma gives str for itself once you wear it), so i went and put some items to stash. After i clicked on body the second time, the game screen lagged and i clicked on unequipped boneflame in my inventory too, which instantly disappeared from cursor slot and another gear from dead body item taken place of it in the inventory. Good i havent clicked on enigma 2 slots off boneflame. Bad it was perfect boneflame for prebuff and I spent week finding it on bnet, I am so much frustrated.