Essence From Waystone Modifier Didn't Spawn in My Map

I opened a T5 waystone in a Savannah map. I died horribly, and then opened up another T5 waystone in the same map, but this time the waystone had an essence modifier (area contains 1 additional essence). I don't know if it is related to the fact that I had died in the area, but I scoured the whole map and there was no essence monster.

Possible steps to reproduce:
Open a waystone in a map.
Let your character die.
Open another waystone with the essence modifier in the same map.
The area won't contain an essence.