Help astral fire and umral ice not showing up

[(Wulfstan)]

To start of with I am a level 60 Black mage. I am not sure if this is a glitch but I am trying to complete the duty where you fight the warrirors of darkness but when I do my rotation when I get low mana umbral ice will not not happen even though it should so I use mana regen and wait for my mp to up enough but no matter what I do astral fire and umbral ice will not appaer. So I ask am I doing somthing wrong or is it a glitch. This has also happened a few time in the void ark as well.

[Promestein]

Some enemies(2nd boss of void ark, bismarck if you dont ride his back) prevent you from getting beneficial effects(Astral Fire, Umbral Ice in this case) from your attacks. Most of the time it means they are invulnerable so you need to change target or perform specific action.

[(Wulfstan)]

Originally posted by Promestein:

Some enemies(2nd boss of void ark, bismarck if you dont ride his back) prevent you from getting beneficial effects(Astral Fire, Umbral Ice in this case) from your attacks. Most of the time it means they are invulnerable so you need to change target or perform specific action.

Thank you, I could not find any info about this online.