Hi,
Is this port delivering Power to any PoE device ?
If yes, what is the device (référence, and PoE consumption) ? What is your switch configuration ?
Do you have any other PoE device ? If yes can you try to exchange the end-nodes to check if the problem follow the device or is on the port ?
If the problem follow the device this could be relevant to pre-standard PoE device or misconfigured PoE options on your switch.
Bye.