Are you powering your MR30H from a switch that can deliver 802.3at power (aka 30W)? You'll need that to be able to offer 802.3af out (15.4W).
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.
The use case of having any MR connected to the PoE port on an MR30H would not be a supported topology; DHCP from other MRs are not forwarded in order to prevent weird mesh topologies from forming. Other devices, such as laptops, would work just fine because DHCP packets are forwarded.