In the Heroic Strike "Tree of Probabilities", the boss became stuck in a wall upon progressing into the locked room for his second phase. All other enemies were killed in this room, and the boss did not appear, with a radar indicator showing that he was present in the corner of the room inside the wall. Through well placed grenades at a small hole in this wall, my team was able to force into phase 3, which upon arrival locked the room and spawned enemies, but the boss did not appear yet again. With no way to get back to the boss, we all were forced to abandon this strike at the end without completion.