This seems new to me, but my tank mercenary keeps entering a state where it can no longer find pathing and just starts running and warping around. It seems like something breaks all of a sudden and then the behavior continues until I suspend and then unsuspend the mercenary. It happens both when I am on the move, or even if I am standing completely still while in combat. The tank mercenary will be holding aggro on the mob, but continue to warp and run around, often pulling the mob with it. This is incredibly disruptive, as should be pretty obvious. Having to stop what I'm doing for five minutes at a time to wait on being able to unsuspend the mercenary is a stop-gap solution, but it's not ideal when the bug reappears after a short period of time. I first noticed this in the Dead Hills instanced missions (Into the Hills and Scouting Ahead). It possibly also happened in the Seeds of Destruction version of Blackburrow, but the effect was very quick and I didn't really stick around to investigate as suddenly half the zone was coming at me. I only mention that as I can say for sure it happens in instances, but I am not sure it ONLY happens in instances (I was not in the instanced version of Blackburrow at the time, chain aggro is bad enough in Blackburrow on a good day if you aren't careful).