Hitting a loading screen on entering a boss arena... is bad.

Tell me how entering a boss arena triggers a loading screen?

I can see the boss and the arena and the fight actively happening... but clicking on enter arena triggers a loading screen so my character enters the arena and I die because I can't control the character, since screen is black with gear animation. But I see my UI, and the health pool going away as I get trolled into oblivion.

Just seems like a strange situation.