AirPlay not working on my iMac
I've got a strange problem. I can connect to my Sonos One SL from every other device that I have, including an iPhone X, a MacBook Pro, and I can even connect to it via the Sonos S2 App on my iMac and the Spotify Connect App on my iMac.
But... when I try to connect via AirPlay from my iMac, it fails every time. I don't understand why all my other devices and even some apps on my iMac can connect, but the AirPlay is not working.
All software and operating systems are up to date on all devices. I've tried power cycling (which is not practical if I need to do that every time). It is clearly something buggy on the iMac, since even my MacBook Pro and iPhone X work.
Any suggestions?
iMac 21.5″ 4K, macOS 10.15