Bug with Grand mirror in digsite map

When I did my first grand mirror it was on a digsite map. When the boss of the map dropped pillars the 2nd boss got stuck and became unable to be damaged in the rubble. While I could talk to elder maddox. I could not complete this stage of the quest and did not complete the map.

https://www.reddit.com/user/Fidwif/comments/1tvb0uv/bug_with_grand_mirrors_in_digsite_map/

Reply to add a reddit post with the image that I failed to upload