This is still happening.
It seems to affect wolves ALOT. Flame, Fire, Dire, Icy, etc. Does not seem to matter what the pull size is. I've killed a lone icy dire wolf and it vanished before I had a chance to loot it. I'll sometimes have the loot window open, and it will vanish before I can click on loot all. Sometimes, I'll have it killed, selected and click loot only to have no window pop up because the corpse has insta-vanished.
This is annoying.
Please fix.