I have a very similar issue, and I can’t really help you. In short, for me, I found the bandit, talked to him and obtained the letter, however, the question “question and Answers” is just blank = there is no objective. I am not sure how to proceed with this.
In regards to the letter, once you complete the pestilence quest, you will be given access to the barn where the bandit is. Have you gotten and completed the pestilence quest?