Hi @WarrieTweeter apologies for the late response.
I am also sorry to hear that you are experiencing issues with the quest Amber Sun. I can confirm that this is a known issue. The development team are intending to fix this with a future update, however we are unable to confirm when this will be.
Please keep checking the news and announcements forum for updates as this is where all of the patch notes are posted.
In the meantime another player has suggested the following workaround which worked for them:
"I fought Balor using only bow and arrows. (I am at max lvl already so very high damage output, so some variance of this may be possible, but I believe it involves an issue with the cutscene that plays when you bring Balor's hp to 0 normally).
In the second phase after Balor removes their mask, I shot each of the weak points while Balor is still charging their sword with the eye laser. Then, I used an arrow stun attack to bring the rest of their hp to 0. After the stun attack, Balor is at 0 hp and on one knee. I attack once with a melee attack (personally using greatsword). This triggers the "kill" cutscene except Balor goes into an A pose and the camera just swivels around. When that ends, Balor remains in an A pose. One arrow shot to the top eye ends the fight and triggers Eivor to pull the spear and return to Ireland."