Flling in the VLAN field for a user does nothing, here's a user with VLAN 200 configured.
root@OPNsense:~ # cat /usr/local/etc/raddb/users
TestUserwithVLAN Cleartext-Password := "password"
Framed-Protocol = PPP
Did you enable VLAN Assignment in General?
Thanks, I'm blind obviously! That did it. PEBCAK :)