Loot from the Kael’thas Sunstrider encounter in The Eye disappeared a few seconds after opening the loot window.
I got Mind Controlled and died on the first pull and I did not check the loot during that pull. On my second pull and successful kill I checked the loot after the 7 weapons which spawn during the encounter and the loot disappeared before I finished reading the descriptions of all 7 weapons. After killing Kael’thas I opened his loot window and started scrolling down and it disappeared before I made it to the bottom.
I killed the other 3 bosses in the instance and they did not repeat this behavior that I noticed.
Nothing was mailed to me and at least one item I saw on the body is not in my inventory so I am certain it was not auto looted.