Hello All,
We are cautiously optimistic that this issue has been resolved in the tvOS 13.2 beta, as a few other users have reported.
To provide some insight into what’s going on here: Our technical investigation concluded that Apple broke AirPlay playback from all non-iOS sources in the initial tvOS 13 release. iTunes playback worked correctly when playing to a single AppleTV zone, however grouped zone playback would fail on the AppleTV whenever non-AirPlay 2 devices were added to the group. Other applications like Airfoil are similarly affected.
-John