Uniti Nova won’t act as master in Multi-room

Hi all,

I have a brand new Nova (amazing by the way) and Qb, as well as a Mu-So which is a couple of years old. The problem is that although I can see all three devices in multi room mode when using either the Qb or the Mu-So as master, I cannot see either the Qb or the Mu-So when using the Nova as the master. They are all on the same network, no extenders or repeaters; just a solid mesh network. The issue is the same whether the Nova is connected via Ethernet or operating wirelessly. They are all on the latest software too  

Any suggestions?

Many thanks in advance. 

Steve