Are there any CableCard gurus here?

I have a sorta strange problem. I'm a new Comcast customer and have a CableCard in a refurbished Tivo XL4. The card seemed to activate fine and I can receive nearly all the channels I should receive EXCEPT 7. Those 7 are all "local" HD channels, and the numbers are near each other but not contiguous. I can receive the SD versions of those 7 channels, so it's not an emergency.

Someone on a Tivo forum suggested I use the Tivo diagnostics to look at those channels, and it seems all 7 are subchannels of the same frequency (309000). Someone else suggested that the CableCard does not know one frequency from another, so it might not be the card. I have an X1 box too, and it receives those 7 channels fine. Does anyone have any ideas? Thank you very much.