Essences Vanishing

I've been farming essences for most of the league, and every six or seven maps, I'll have an essence monster vanish mid-combat along with all the loot that would drop off him. It often happens about a half second after I open the essence, and the monster will simply vanish. If he's the last one on the map, the count of monsters go from 1 to 0, but his loot is gone.

Oftentimes, if this happens early in the map, it will happen more than once per map. I've had up to three essence monsters vanish into thin air.

Followup. Essence with 3 horrors and 2 hysteria on it just vanished. One monster left on map is the boss. Killed the boss, 0 monsters left. Lost just shy of a divine because the essence monster vanished into thin air with all its loot.