All the documentation states that ports 11/12 on the MX-68 are PoE+ ports, yet only port 11 will deliver PoE power. I was connecting two Avaya VoIP phones, but only port 11 will power the phone, but I can use port 12 as a regular LAN port. Is there a different power supply needed to be able to power both PoE+ ports?
The two PoE ports are identical and there is only one power supply model. So if port 11 is working and port 12 isn’t (assuming you’ve nothing plugged into port 11, and so can’t be over the PoE budget), then I’d log a support call as you may have a faulty device.
EDIT: I’m assuming you tried swapping the phones around to make sure it’s not a faulty phone or a phone configuration issue.