same thing happened to me, try to rush in to the middle but the scripted event will port you back behind the frost wall, when start attack, ally nps will walk through the wall but you stuck behind.https://postimg.cc/zyCkNLRZ Even if you managed to ranged the 1st stage four boxes, next stage targets is at the opposite wall...https://postimg.cc/v1QZBm36 Update for fixes:invite my guildie to go into my story, this time the frost wall was breaked by Rytlock, this was not happen when i play alone, even exit game, quit episode and continue again few times, so for temporary fix if you encounter this bug, invite someone (may need he already done the story?) to play with you for the last episode.