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.