I doubt it’s a malfunction of the Arc Ultra as it has no way of determining from where the audio is coming from such as an announcer vs a referee. Depending upon the broadcast source I’ve noticed on occasion the referee’s voice  may be lower than the announcer. Also, remember the referee’s voice and crowd noise are being captured by the source as secondary audio vs a direct transmission by the announcer.

Agree, I never really considered it was the Ultra but more a setting. I think it’s the source. When I play movies the surround is there but on a hockey game is mostly centre channel. Thanks. 

When you’re experiencing sound that isn’t as you’d expect (eg hockey), what audio format is showing on your Now Playing screen on the Sonos app (the screen will be mostly filled with a TV icon, and below that is the audio format that is playing on the Arc Ultra). 
And when you play movies, are they streamed or Blu-ray and what audio format is showing then on the app?