1) Things take awhile most times as its using a queue system.2) Just because it's available in testing or stable does not mean its ready as it still takes time for the mirrors (where you are likely grabbing from unless not using the meta link) to see and sync with them and the fact that these happen generally on average for the busy (primary) mirrors @ 8am 2p 6p 10-11pm US East Coast time (they can take 30-90 minutes to sync ) which is also not the same frequency that yum /dnf are set to sync/update metadata (or you would never stop sync and updating to be totally honest (which would never be "stable").
Hope that was layman enough, if not please let me know what needs clarity I will be glad to impart what I know/understand as are several others here I'm sure.