Not that it puts this in perspective, but one of my kids transferred from a rather expensive private institution to CU after his sophomore year. He had great grades, IYAM. (Okay, that sounds like a brag, but there's a point here.)
CU would not transfer one class, something in English because either it duplicated something required at CU or wasn't good enough for CU for some obscure reason.
We didnt' know until he transferred that that class wouldnt' count towards his degree. It looked to us like English Lit was English Lit, but it didn't to CU admissions.
In his case, no big deal, just that we'd paid for a class that he'd have to take again. But if you needed X credits to transfer from a JUCO, and had a class that CU didn't accept, it would be a big problem. They didn't like a class from a 4-year university with a good student, and presto! they weren't going to accept it. No argument.
who/why was the ball dropped with Simmons, I don't know. But this stuff doesn't just happen to athletes, it's just a function of transferring from one school to another. I can only imagine Hawkins and the others have been scrambling as hard as they can, making calls, trying to do anything to resolve this.
They want to win, they want Simmons here, they want success, too. Why would they not try as hard as they can to get him enrolled?