7502 behavior with connected DL380 NIC team

[RudyW]

One of my server guys set up an HP DL580 running Windows 2012 Server and connected two NICs to our HP 7502 switch. With autonegotiation enabled on both NICs and on both switch ports, one switch port negotiates to 1 Gbps full duplex and the other port to 100 Mbps full duplex (FD).

I found this behavior to be odd, so we began to troubleshoot. We found that if we hard code one NIC and the corresponding switch port to 1 Gig FD, the switch port comes up upon noticing the Ethernet link, then becomes blocked by MST. If we set the NIC and switch port back to auto-auto, they still negotiate to 100FD.

Both switch ports are configured as such:

   interface GigabitEthernet2/0/12
   port link-mode bridge
   description DC1 team
   stp edged-port enable

And all the defaults are taken on the NIC team.

Any clues on what may be causing STP to block the port?