I'm hoping this isn't a bug and that I'm just doing the quest wrong. I'm co-oping with a friend. Once we spoke to Gareth in the Seeker's hideout, he marked a rally point on the map. We reached Gareth's Rally point, where the other Seekers had gathered but Gareth wasn't there, so we tried to proceed anyways. The Seekers follow us to the stairs then run for the boat. We can't interact with the Seekers or the boat and are left to fight the Bishop by ourselves.

Where's Gareth? Are the Seekers supposed to just bail on us? Is this a bug or am I seriously screwing this up?