I specify this is in the Welkin's Reach Bastille of Might, but I doubt it's specific to just this one. This impacts the event where you're locked in an arena (exits are barred) and face waves of enemies.
When the Bound teleporters start spawning in, they can teleport OUTSIDE of the Bastille - preventing you from killing them and finishing the event. You can't even shoot through the gates. The only way around it is by praying they teleport back in, or having a companion that might walk through walls and chase them outside.
