I guess you've checked the obvious parts but it might be worth checking the controller has HTTPS access to edit.meridianapps.com ? Just a note I cannot ping this URL so I expect this is the design, it does however resolve to an IP.
The controller will also need a valid and working DNS server to be able to resolve this URL (this may require a reboot to take affect).
ip name-server <dns-server-ip>
Do you also see the beacons on the controller?
show ap debug ble-table ap-name <name>
Is there any errors in the update status?
show ap debug ble-update-status