Essences monster disappearing and does not drop any loot

I have been playing essences for a week and I noticed that sometimes the essences monsters will disappeared after killing it and will not drop any essences. I have encountered it multiple times and even lost my duplicate essence of horror and delirium.

I am playing a Poison SRS build with bone offering, taking essences on map device, taking all the essence node on the atlas tree. I am not sure it is due to my offering or a texture bug or atlas passives.

Please fix it, I am losing a lot of essences with this bug.