1 HD station is displaying in SD on Comcast?

Wanted to check to see if this is a Comcast or TiVo issue.

Am a Comcast sub in Richmond VA.
Channel 846 - Comcast Sportsnet Mid-Atlantic HD = equivalent SD channel 4.

What's displayed & outputted on screen is SD & not HD even though the info on my TiVo is showing 720p; the picture quality is definitely SD.

I compared side by side with other TV's in my house & what Comcast is showing for CSNMA on all the screens for 846 HD is the same as SD Channel 4.

Comcast issue or a TiVo issue?
Feedback?

1 HD station is displaying in SD on Comcast?