So before I burn a few hours finding a team and then running through the full raid...
Today I found a husk of the pit. Killed thrall until it turned into the Eidolon Ally. Upgraded that until the only node left needs the Essence of the Oversoul...
However, I never received a questline from either Speaker or Eris. I'm wondering if it might be due to having a year 1/2 Eidolon in the vault? I just deleted it to see if that would make a difference, and no luck, despite leaving/heading back to the tower and changing between characters.
Any ideas?