@ubi-spacecats
I tried to restart the game, unfollow the other quest, restart the xbox, nothing helped.
I played 222 hours in this game. I went back in time (219 hours savegame), I had the same problem, so I went back more to 217, and the Arena is working now.
Cold embers: there is an other funny story... I killed everybody too soon, and it said: the guy is going to try the ritual next night... but he didn't. I found some players who had the same problem.
After that, I decided I complete some side quest... I tried the one where is a hammer in the middle of the lava, then I woke up in a prison. I should talk with the guy, but I couldn't...
I really understand, that it is a big game, a lot of opportunities in it... but still... i just cannot play it. I'm looking forward to the update.

@ubi-orion
https://www.xbox.com/play/media/3H6XEP5P

There is a gameplay, you can see what happens in the end of the video

Hi there,
i entered the Valkyrie arena, I finished 3 rounds, than I cannot leave the area. There is an invisible wall around the arena. I cannot collect anything, I cannot fastravel. I finished the 3 rounds but I’m still part of the mission. Any idea?