Hmm, see if the following works for you....
Delete all tuner profiles, then create an "ATSC 1" profile:
Tools > Options > Television > Setup > check two boxes "clean up channels" and "clean up guide data" > Next > choose Antenna method > Digital ATSC select tuners 2 + 3 > Next > use OTA for guide > next > click SCAN > after scan is done, perform "load program guide" (takes a long time, even though I deleted all the "extra" sub-channels).
Add another profile for "ATSC 3"...
Tools > Options > Television > Setup > Next > choose Streaming method > use mc2xml for guide > next > click SCAN > after scan is done, perform "load program guide".... somehow, don't ask me how, it picked up the correct guide info.