They list schools even if they don't have all the usual data for them yet. If Mayo AZ isn't listed as a separate school they probably never will be, and are just considered a subdivision of Mayo. For example, CCLCM isn't listed anywhere on its own, it's considered part of Case Western.
Edit: Yeah looks like this is the case, Mayo is considering AZ and MN as two campuses of one school. See
this screenshot from their website showing that they're using all 100 students from the two campuses combined to generate their median stats