Can't destroy "Dark Energy" in Act 12, Chapter 2

[Harpy Monet]

As the title states, i can't target/destroy the dark energy "eating away at Chundoon".
I've done this quest on different characters already, never had an issue. I just used some aoe attacks in the general direction and could easily destroy it, but on one character (female lyn blade dancer) i just can't get it done. Ive tried exiting the area and redoing part of the quest already, nothing worked. This stops me from continuing the main story and blocks access to the entire Northern Continent, so it's quite annoying.
Any ideas what i could try?
Merry Christmas