I have encoutered exactly the same problem, yeaterday. I have two H9 Core and one H9 Max. So my assumption was, that it does not offer to MaxOut Core as I have Max….
An account holder has the right to upgrade ONE non-H9 Max pedal using the MaxOut program. Once an H9 Core or Standard has been converted in this manner, this account can no longer upgrade other pedals in the future. Did you purchase your H9 Max or did you already convert another H9 this way?