Drew has hit it - you can't VLAN the "wrench" port. What you are trying to accomplish is based on a misunderstanding of what the "wrench" port really is.
The wrench network port on newer controllers is not e0M. Rather it is literally the "wrench" port. Internally, there is, for all intents, an Ethernet hub/switch that sits just behind the wrench port. The hub has three ports - the external wrench uplink port, and internally the SP network port and the e0M management port. Physically the SP port does not site behind the e0M port - rather they are both connected to the internal hub at the same level.
So - even if e0M did support VLANs, because the SP port is not behind e0M the strategy you want to implement wouldn't work.
To accomplish the same goal, if you need the SP and "management" connections in separate VLANs, may I suggest that you use the wrench port only for SP connectivity and then assign the wrench port to a specfic VLAN at your network switch. Then, define one of the other network interfaces available (whether e0a, e0b, or if you are port channeling those together perhaps "a0a" or another group name) as a trunk and add your management VLAN and a logical network interface to that trunk. Define your management network interface through the VLAN on that logicial interface.
Works well in both 7-mode and Clustered DoT if you head that route in the future. Of course the other option is to just let the SP and e0M live in the same VLAN.