Also running MC 17.189 and just got Hdhomerun (dual) and cannot find any channels on the channel scan.
HDHomeRun setup scans and finds many channels.
WMC runs and finds/tunes channels.
But when I switch the hdhomerun application to "J river media center", then run MC and do channel scan, it takes a long time to find nothing.
Firewall is off, I tried running MC as Administrator, I tried just about every type of QAM digital scan.
HDhomerun is tuning Verizon FIOS clear QAM. I assume this is type "QAM Standard" in MC (though I've tried them all).
Let me know I should post elsewhere.