" It was originally 208V 3 phase, but somebody screwed up and ordered a 240V single phase generator. Since there are no 3 phase loads we replaced the panel with a single phase. "
I hope someone did their due diligence and confirmed there were no mwbc with 3 circuits sharing one neutral. I can't imagine any 3ph panels, feeding lighting and receptacles that didn't have at least some mwbc home runs. Changing one from 3 phase to single phase would require some homework in that regard for sure.
Brian H. " No, I think you mis-understood. I said I'm an electrician, not a magician."