Obtained this quest line (Wrack & Ruin) which is part three (?) in the series.
Found the first of the two serpent eyes. (edit: right eye, Found again)
While in the quest area for the second eye, found a mini dungeon (some cellar) can’t find record of it’s name anywhere in chat or challenges for completing it. As the area is greyed out as if I never explored it.
EDIT: going back for the second time, re-exploring the area, I found the Cellar (slimy Cavern) that I had completed. It shows as completed, even though the game thinks I’ve never explored the area before.
Upon leaving (the first and only time), the quest line reset to the point where I had to find the door at Yngovani again, which progresses the quest to find the left and right eye again.
The first eye that I found before is not in my inventory anymore, so I have to repeat this again.