Hi Andrew,
Since I only saw 1 command under the "Extreme config" I would go ahead and mention that make sure you have "create vlan mgmt99 tag 99" command in there too.
that will specify the "vlan ID". right now the switch looks at the "vlan name" as "mgmt99", tag could be something else...
I ran into it once.
Also make sure you have already taken care of "configure default delete ports all".