It happened at the start of the third, cube encounter. At the start of this encounter i could not place a rally banner, then after starting mobs didnt spawn for several minutes, when they eventually decided to spawn, they bugged out completely and stopped reacting, almost like i lost internet connection but i didnt. I remained in the room for several more minutes until getting guitar errored, i can only assume something weird happened with the mob spawns to cause the error. I would also like to mention another bug, when i loaded into the dungeon i got immediately shown the wipe screen. I re entered it from orbit in case that bug would have affected flawless.