I think the original problem was actually Apple setting similar restrictions to the 4K Apple TV with the update a few years back (TvOS14). Using Apple music you could play to all devices from your apple TV, but not so using Pandora or other streaming services. That has been resolved. I now seems Apple has put a similar restriction in MacOs after solving it on AppleTV. You used to be able to airplay to multiple devices. Now you can only play to one. iOS still let's you airplay to multiple speakers though
... View more