Cruel Act 2 Ascent to Power and Traditions Toll Bug

The quest Ascent to Power is stuck at Travel to Traitor's Passage, which I have found in forums to be a common issue. However, after this, I encountered another bug in the same area, which happened once I picked up the Final Letter from Tradition's Toll quest. The quest now states that I must deliver the letter to someone on the caravan, but Shambrin is never marked for delivery, as is no one else, and this quest has also become uncompletable, but now forcing me to carry an item in my inventory and refusing me two passive points.