Exact same problem as this thread.
https://discussions.ubisoft.com/topic/88072/can-t-start-kingdom-s-end-quest-after-pledging-to-hamtunscire
The Hamtunscire quest is not triggering upon pledging.
I tried an earlier save and did the entire Norway quest again and the same problem.
I recently upgraded to Xbox Series X and the problem is exactly the same. Tried leaving animus, Going to Vinland, Changing gender. No work around.
Also the most recent patch did nothing to fix this.
I have clocked over 200 hours in a game I literally can not finish.
I sure as hell am not buying the DLC (which ironically I was looking forward to) until this is fixed.