Fractal bug.
This isn’t a bug, you just misunderstood the charr in this fractal.
There are two types of charr at the beginning of this fractal, those who follow you, and those who don’t. The charr that follow you will still attack the ever-respawning enemies at the beginning of the fractal, but if you kill those enemies quick enough, you can get them to follow you away from the spawn point. The charr who do not follow you will always fight the ever-respawning enemies, or run into arrow cart fire and get killed immediately.
I figure what happened at the end of the fractal was just as your last person was downed, the charr killed all the enemies at the beginning of the fractal simultaneously, didn’t have anything to fight, and teleported to the closest player, who just happened to be downed at the boss.