My sound with Comcast, San Francisco, was fine. There were lip sync problems in the beginning and a little bit at half time. I thought it was funny that the game itself was 2 channel stereo but the commercials were DD 5.1.
I have this problem with dish during the game (had it with comcast on INHD2 before it became NFLHD when they aired games for testing) and posted a q in the AV audo forum about my receiver and I don't know what's up (and noone has responded to date). If I put my receiver on 5.1 audio for the nfl game last nite it worked fine but if I put it on DD/DTS like it should be I only get bass. My buddy who does installs for audio/video looked at it and didn't see anything wrong so maybe its the signal in some areas?
Thanks. Ya, all of my hd channels are fine as far as sound is concerned except for UHD, it has always been muted just as you described. NFLHD for some reason has this problem last night with the KC game, but not all the time. Need to call the good people at comcast.