HDHomerun, QAM and TVHeadend = Nogo

Looking for some advice. I’m trying to setup a HDHomerun Extend with OSMC, via TVheadend. The HDHomerun detects the cable channels all on it’s own, and can stream to local devices like my iPhone. The channels are all clear QAM. My issue is that when I try to setup TVheadend, I cannot seem to get it to detect the same cable channels (via the port 9981 interface). I’ve tried to switch TVheadend from ATSC-T to ATSC-C, but I still get no channels detected. If I plugin via antenna, TVheadend finds channels without an issue, but I want the ClearQAM channels.

Useful details about my setup: Ras Pi 3, HDhomerun Extend, OSMC version 1-2018.