So I finally decided to crack my Ultra Moon save open with PKHex to make sure everything I'd been genning with PKSM was legal.
Holy fucking crapsticks is this wop dev a lazy little fuck. Turns out every mon I was genning in my copy of UM was showing it's origin game as fucking Moon. It also wasn't reassigning the geographic region of origin when reassigning mons to my own trainer ID. Damn app has gone through two updates since USUM and the lazy fuck hasn't even added Dusk Lycanroc to his program (much less the fuckload of other features he's been promising for YEARS), and I'm starting to see why.