This is some kind of configuration issue. I tried a new MR33 and it didn't work either. I have also tried using AC and 802.11at injectors plugged into the MR33 that is connected to Port 1 of the 30H. Heck, I even inserted another Meraki MS-220-8P between the 30H and 33.
Hardwiring my laptop in Port 1 works perfectly.
Are MR APs supported when plugged into MR30Hs? All mine just blink amber after giving up after 2-3 minutes.