2 node cluster shows no WORKER

I would appreciate any suggestions on following problem:

I have a 2 node HA pair of UTM 220s running UTM 9.

I have configured them as a closer but the status shows that I have 1 MASTER & 1 SLAVE.

Surely I should see 1 master and 1 worker, otherwise it is effectively simply an active-passive configuration.

The configuration "works" correctly, i.e. will fail over correctly, but since I second node is always a slave I am not getting any benefit of a "cluster" which is annoying as a cluster license is almost 2x the price...

Any suggestions...

Ben