Greetings,
Which model of Supervisor engine are you working with? Older Supervisor management ports have only ever been usable in ROMMON for image recovery:
Sup-III, Sup-IV: "The Ethernet management port (labeled 10/100 MGT) on a Supervisor Engine III (WS-X4014) or Supervisor Engine IV (WS-X4515) is used in ROMmon mode only to recover a switch software image that is missing or corrupted. This port is not active during normal switch operation and cannot be used as a management interface."[1]
Sup-V, Sup6-E: "The Ethernet management port can be used (in ROMMON mode only) to recover a switch software image that has been corrupted or destroyed due to a network catastrophe. When using Cisco IOS Release or later, this port can also perform the same functions as the console port. For earlier Cisco IOS software releases, this port is not active while the switch is operating normally."[2][3]
Kind Regards,
/Phil