Originally Posted by
Deceiver
That's awesome, maybe it has to do with a combination of the new groupset, center mount, and position on the bike. It looked like Shimano has 28mm as the widest for those too but if it fits it fits.
Wondering if an upgrade would accommodate that other wheel I have sitting here that I can't presently use.?

Do you know anyone with a newer direct mount brake bike? There's tons of them on the market right now. I'd ask to drop by someone's home and see if your wheel can slide in. If so, the $50 "upgrade" to the new brakes is probably cheaper than tanking the losses on selling an individual rear wheel and/or buying a replacement.