From the Policy Manager firmware release notes:
Policy Manager supports the use of VLANs on ExtremeXOS
devices using policy functionality with the following exceptions:
- VLANs cannot have a name containing "SYS_VLAN". VLAN names containing "SYS_VLAN" are automatically changed to the VLAN ID (VID).
- VLAN names can only contain alphanumeric characters. All special characters and spaces used in VLAN names are automatically changed to an underscore "_".