Corrupted strike, you get stuck in a room with a door instead of the cave that leads to the big drop/jump. Hollowed Lair strike, you get stuck at the door to the mob fight that ends with a Walker. There seems to be a systemic problem with joining/spawn points, and it's getting worse. Edit: another piece of joining genius just observed; I was 'joined' into The Corrupted at the end, just as the chest appeared. Edit 2: And another: in the Scarlet Keep strike, if someone is slightly slow and Joining Allies occurs as the elevator starts up the shaft, the whole team will get stuck at the first stop (crystal shield never goes down) and can't advance.