So I know that Big Sur is not yet approved for Indigo, but I've got an instance of Music running on BigSur and it connects to the Indigo Server running on Catalina thru the iTunes plugin just fine. Everything works as expected.
But Air Foil on Big. Sur, isn't populating speakers back to the Indigo Server The main Air Foil "device" is shown, data for songs etc is populated as expected, but no speakers.... I've got a somewhat complicated audio system... usually running Music from yet a different computer also running Catalina, and everything there works just great, so this Music on Big Sur setup is just for the holidays.
its been so long that don't remember how one adds AirFoil speakers... I seem to remember that was done automatically... but in this case... with Indigo Server on Catalina, and Airfoil on BigSur, speakers aren't being populated....