Skeletal arsonist targetting bug

Skeletal arsonist have some problem with the targetting system or projectile behaviour issue, prime example is abyss map boss, arsonist target behind the map boss so it never hit the boss itself. Other things that i encounter is also in some boss, the projectile seems to bounce of, so the grenade go all over the place, i dont know if all of them actual hit and this is just a visual bug but i think the single target dps feels low so i asume the projectile get bounce off or something.