Why do Stormfiends and Bile Trolls create level barriers?

This can be totally game ruining on Athel Yenlui and god knows where else, especially if it pops up just as you drop down after the giant forest with the two tomes & grimoire in that small area before the cave. Bosses typically bring hordes and this issue ruined a Legend game.

I’ve also seen pictures showing that the bosses sometimes either don’t aggro or just bug out and the walls remain. What gives? And why do these exist?

Barriers with bosses exist to force you to fight the boss, instead of just speedrunning past it.
These barriers aren’t limited to any specific kind of boss.
Of course it’s annoying if the boss refuses to fight you.

My guess is, is that those two bosses in particular are slower then the heroes and fatshark were worried people would just run.

But yeah it’s frustrating at the moment as the bile troll tends to bug out and soft lock games with his lame barrier.

But you can’t run from enemies. They have holes everywhere to catch up to you and they don’t despawn. Everything moves faster than the players and only in very specific circumstances can you get significant distance from the bosses.

But they’ll be back, and they typically bring the hordes with them upon spawn.