iTunes Remote not working

None of my devices (iPad Pro and iPhone X on 11.4 beta and iPad mini on lates released version) cannot conenct to iTunes Remote since latest Mac beta update (10.13.5 17F70a). launching iTunes Remote on each device 'sees' my Apple TV and my iTunes Library and will connect to TV. Trying to conenct to iTunes eventualy fails with error message: 'iTunes Remote can't connect to your iTunes library. Check your network settings and try again'.

iTunes still sends music to my HomePods - I jsut cant make any changes from a mobile device (clearely it is not a network issue!). No change after rebooting all devices (inc Mac).

Suggestiosn for a fix appreciated...