I have connected a Roam to my network tonight, a gift for my daughter. All software up to date on IOS, App and MacOS.

 
Roam (gen 1) is brand new (bought during the final offers at Roam 2 launch) so unboxed. It has connected fine to my network. Weirdly, it will only play music when grouped with some of my other Sonos devices. When it isn’t grouped, it says that the music source is not available - even though it is and working fine for every other device. How can I sort this easily?