The seconding building inside the wall in the Grave of Ancients zone is bugged. When I climb to the second floor, I can no longer use cover or engage combat on my own. I’ve tried this numerous times with several saved games and even if I leave that building I can no longer use over or engage. Weird, i know, but it happened. Thank you.
Can confirm this happened on both of my playthroughs
Thank you for bringing this to our attention 
I’ll have it reported to the dev team right away.