Scene was only recalled back at the shop, so no idea if it would have fixed things onsite.
Wasn’t channel balance – all inputs were mono and panned center. Patch was checked and inserts were disabled as part of troubleshooting. “Meters working” was the main L/R meters with nothing PFL’d indicating both L and R at the same level.
I’m perfectly willing to chalk this up to user error, but I’m trying to figure out what the error might have been. Especially since I’ve not been able to find anything on the console or in the reference materials for how to even treat the two sides of the main L/R bus separately (other than the pan/balance controls on the channels and buses, all of which were checked)