My bots did something super strange during a Nexus run yesteday, while moving to the void boss 2 of the bots headed to dragon boss, i didn't notice at first, but i stopped them and went after them, then suddenly my 2 other bots decided to keep going for cave entrance to the stone boss.. So i can only assume that when moving on those bridges in nexus sometimes the bot decides to generate a path through the whole instance to get to the tank/follower which isn't even possible, because you jump down at the stone boss.