Slain archfiend still debuffed ascension run

[Ardub23]

I just finished a run on the Hardfought-US server in which, despite having killed Geryon, his debuff still applied to the ascension run. The end-of-run summary included "Geryon was weighing you down" in the final attributes, and Geryon was listed among the creatures vanquished.

I suspect this has to do with the fact that Geryon's lair in Cocytus was a bones level. He'd killed the previous adventurer, so I assume he was already somewhere on the level before he teleported to me. I don't know whether the same thing would happen if an archfiend appeared in a bones level other than their lair, or if a bones lair didn't have the archfiend already spawned in.