Tried your suggestion of scanning without the splitter. Tried these...
1: No splitter, with antenna amp, first tuner connected by itself, the second tuner totally disconnected, rebooted computer... same error dialog.
2: No splitter, with antenna amp, second tuner connected by itself, the first tuner totally disconnected, rebooted computer... same error dialog.
3: No splitter, no antenna amp, first tuner connected by itself, the second tuner totally disconnected, rebooted computer... same error dialog.
4: No splitter, no antenna amp, second tuner connected by itself, the first tuner totally disconnected, rebooted computer... same error dialog.
The HD HomeRun Config.GUI was showing 100% for all tests both with & without the antenna amp so there is plenty of signal. I get 135 channels here in the Houston, TX area.
Also ran same 4 tests on the HD HomeRun Windows TV software & all ran well.