When in transparent mode the mgmt vlan1 is always untagged. ScreenOS expects the device to be in a single broadcast domain and the ip address for management in untagged frames.
I am pretty sure this is not configurable.
I would also test to see if ScreenOS can process rules on the tagged traffic. The expectation of transparent mode is single broadcast domain. So there is a possibility you will not be able to inspect and write rules against the tagged traffic.