The other day, both me and my brother were playing. He stepped toward the boss just a little quicker than I did, and I was almost completely locked out. I say almost just because while the boss could not physically get to me, he could and did roast me. I think it would be good to pull everyone in the party into the fight area if there is going to be some kind of mechanism in place to keep people from leaving (and entering) the fight area. Either that, or let someone who is not in the fight enter the area (make it a one way). It is extremely frustrating to get locked out of a big fight you want to participate in.

I didn't know if I should file this as a bug report, QoL, Environment, or Enemies issue - so I just picked one. Feel free to move this if I didn't pick the right one.