The problem seems to have to do with when it initially spawns. There is supposed to be a Mane in the center of each summoning circle, but sometimes it's one of the later demons (Barlgura, Glabrezu, Balor). When this happens, there is no opportunity to get rid of all the summoners because once the Balor is down, no other demons appear to trigger the summoners.
Harper Chronicles: Cap Snatchers (RELEASED) - NW-DPUTABC6X
Blood Magic (RELEASED) - NW-DUU2P7HCO
Children of the Fey (RELEASED) - NW-DKSSAPFPF
Buried Under Blacklake (WIP) - NW-DEDV2PAEP
The Redcap Rebels (WIP) - NW-DO23AFHFH
My Foundry playthrough channel:
https://www.youtube.com/user/Ruskaga/featured 0
Comments
"Avernus HE spawning incorrect amount of enemies (Fixed in next patch)"
I was next of the HE place, the HE was NOT up, and I was targeting a Mane undeground... the targeting was going on and off, as the Mane was going up and down under the ground.
Cool, uh?