Well, don’t know how common is this, but once such thing happened in my game too. I payed a visit to the camp of high level bandits and one of them got up. I chose to run, but he kept being right behind me, not allowing to somehow change this situation. Ok, we stopped in the field, and I decided to try fighting him tet-a-tet right under the moon. He was obviously good in combat and better armored to I decided to place my bet on master strikes at least in the beginning.
After couple of minutes of dancing around each other I understood that my plan has failed. He wasn’t attacking. Sure, he parried, beat me in the face during clinch, stuff like that, but he definitely wasn’t going to give me window for return strike. So I had to run all the way to Sasau, having him right behind me, trying to get some distance to call the horse and turn the uneven fight in equally uneven race of mounted archer and plate-armor swordsman.
I can’t say, that is a “bug”, just seems like AI needs some tweaking in it’s combat strategy.