Not sure if it's only me but during 2nd and 3rd wave sometimes during boss Fight , all my characters usually lag out.
When i attempt the fight then again it seems to work fine.
To clarify what i understand with lag out, its like the whole zone crashes and i am unable to perform any action for like 1-2 minutes than all characters return to character screen and i am usualy at a spot like ZI before i started the fight.