[mythtv] Has anyone tested channel scanning in a us-cable Clear QAM environment?

[faginbagin]

I ask because I can't get mythtv-setup to find any channels. I first
tried a scan before running mythfilldatabase as mentioned in this email
thread on mythtv-users:
http://lists.mythtv.org/pipermail/mythtv-users/2020-January/402291.html

I just tried another channel scan after running mythfilldatabase.
mythfilldatabase added lots of channels and listings to the database,
but the channel data looked incomplete. So I did a full channel scan,
which said it was scanning for ATSC channels, not QAM, and found no
channels. I can't find any channel scan settings that distinguish
between ATSC and QAM.

Not surprisingly, the channel data still looks wrong. For example, all
of the channel records have a NULL mplexid and the dtv_multiplex table
is empty. Has tuning a clear qam channel changed so much that channel
records don't need to point to valid dtv_multiplex records any more?

FWIW, both "General -> Locale Settings -> Channel frequency table" and
"Video Sources -> MyVideoSource -> Channel frequency table" are set to
us-cable and the listings grabber is "Multinational (Schedules Direct
JSON web services w..." and the listings data looks correct.