I haven't done this quest in a long time anymore, but I think I remember (he's supposd to be in the dungeon north-east of Deshaan, right?)... this marker issue is been there forever.

Unfortunately, that's by far not the only quest where the questmarkers are at the wrong position (some don't even exist, somehow). If I wouldn't have done all the quests 8 (and more) times already, I still wouldn't know where to go (and sometimes I AM still confused even though I've done it before).

One of the "funniest" (most annoying) questmarker issues I recall is in Marbruk/Greenshade where it first leads you outside of the south gate, and when you're outside, it leads you back inside to the north gate. Also quests in larger caves and such often lead back to the entrance instead of the exit right infront of you when the quest is done.
Not sure if they'll ever get it done fixing it...

I agree, questmarkers are essential especially for the main quest. I really hope they'll fix them as soon as possible (it's about time, after 2 years, isn't it).