Tvheadend

setup: tvh4.0.9, rpi3, OSMC
tuner h/w: HDHomeRun HDHR4-2US (2 tuners)

The above tuner device has 2 tuners. I have it connected directly to cable (no card/box), and have successfully configured the first tuner (tuner0) with an ATSC network that contains manually entered muxes.

I am trying to configure the 2nd tuner (tuner1) with a separate network - an ATSC that uses predefined muxes (United States: us-Cable-IRC-center-frequencies-QAM256). I've added the network as described, added it to the 2nd tuner (yes the tuner is enabled), but it did not scan. I clicked force scan and nothing happens. nothing is showing in the log window, or in the status. It's as if it is ignoring it altogether.

What am I missing? Thanks in Advance!