I don't think we have nailed an exact solution for it. At first we believe it was very late at night but some unlocked it at morning so it's still a...
I had "Alice" answer a ticket (pet trade related, which to my knowledge are generally always routed to her to deal with) as recent as within the past...
darkvger is correct, when he was available a few days ago, he did replace Bob as a challenger. Truthfully, I'm not too certain what he may have done...