My problem may have been that I registered for the Kessel Challenge, which includes the Virtual and Rival Run challenge.
That didn't allow the registration of more than 1 person at a time. So, while I registered myself in one browser, I got back in the queue to register my wife in ANOTHER browser.
In the end, I had to do it in 2 transactions, but both my wife and I are registered for the Rival Run Challenge and the Virtual Half marathon.