Bug reporting this as well, posting here to try to get more info on what causes it.
Three eChrono runs today, and after killing the Cojoined Abashai Devastator, at the end of every single one of them, there were six of the orange-named Bearded Devils in the elevated room where the Epic Chest spawns.
Not sure what causes them to spawn/follow people in, but it was frustrating the third time, when we nearly wiped to them while on the load screen between the Rusty Nail and the Epic Chest area.
Just a suggestion to players - if you own a Radiance Guard or Fearsome item, put it on when you walk through that portal at the end.