I finished Coldharbour this afternoon. Just before the final confrontation with Molag Bal I had to destroy three anchors, then plant Meridian's light in the center.

After I destroyed two of the anchors, I went to the third one and waited for Meridian to show up, which she never did. I was looking to see if I could destroy it without her help, but that didn't work. Suddenly, I got a message on the screen to go plant the light in the center space. I did that, and shortly thereafter, without ever destroying that last anchor, we won and the quest was completed.

Except for that, I must say that the final quest sequence was great. and I really enjoyed it.