Hello philip
Everything you mentioned is ok, i have configured a SSID in the 6GHz band.
Started allover again, AP conecxted to dashboard ( 2 hours) then wireless conection to ssid
then conected to ap.meraki.com - configure  changed survey mode to enable 
Same result. when i check the signal strengt with the Airchecck  G 3         2.4 and 5 GHz are ok 
but no indication vor the 6 GHz radio