I have a Mu-so Qb (1st generation) which until recently worked perfectly as an Airplay 2 endpoint. For no obvious reason (other than perhaps recent Roon updates) when I went to play something this morning it would not (although bizarrely on a couple of occasions it did but changing tracks recreates the problem). You can see the purple vertical bars going up and down and Roon says the QB is Airplay2 streaming but the track progress at the bottom of Room remains stuck at 0:00. I am connected via ethernet although have tried wireless without any joy.
I have another Airplay2 device endpoint which is still working on Roon. I can play uPnP (using the Naim app), Qobuz on my iPhone using Airplay and stored music using Apple Music on my iPhone using airplay on the Qb. I can even use Roon ARC to Airplay from my iPhone to the Qb! Just not Roon Remote.
I have tried resetting the Qb as well as powering down the Qb, the Nucleus, the switch and the router and then power them up again in the reverse order.