This has happened to me twice now, so I guess it's a bug. Not sure if it has been posted already though. If it has, sorry about that.
Here goes:
Sometimes when I participate in a tournament and I (and my comrades) have fragged all other participants in a certain match, the battle won't end. The first time this happened, I was the only one left standing. The second time there were also two of my comrades left and they tried to run through a wall of the arena, which of course they couldn't. This leads me to believe that there is a clipping problem where one of the opponents has gone through the wall.
The second time was in the Sargoth arena. Don't remember where the first time was, but it could well have been in Sargoth as well.
You might want to check out the walls there
Niek