Le Loi#2 The Mountain Siege glitch/error?

Path out of map cleared, but the allied army that spawns to exit the fortress just stands around [no buildings near flagged area where they spawn].

They stand around until they're killed by a group of Paladins/Champions that manage to get in.

So I figure the second spawn group will go through. More of the same.

This did not happen when I first beat the mission in Moderate when the game came out. Trying it again in Hard after the latest patch.

Is a trigger broken?