I can't get Pandora to play music on my Apple TV (4th Gen). It just sits there at 0:00.
For some reason Pandora doesn't work with Reduce Loud Sounds enabled.
Disable it by going to the Settings app.
Settings > Audio and Video > Reduce loud sounds > off
EDIT: I just discovered you can ask Siri to "Turn Reduce loud sounds off" as well and it is much faster than navigating the settings of course.