The quest indicates the area where you need to talk to this NPC, but he is not there; he is in a different location, which is why he does not provide a new dialogue.  There is an additional objective in the quest—to talk to Midkongor Mirmal at the top of Meridia's lens, but he is still standing in the same place, and attempting to talk to him leads to the old dialogue. I understand that you can do without this additional dialogue, but it's disappointing when you want to complete the quest by listening to additional dialogues, and you can't do it because of a bug.

