True, I should get a proper error message rather than just an app hanging with a white screen.
Since I'm a Showtime customer via Apple (subscribed via iTunes), I don't even have a login for showtime.com, so even if I wanted to check my clients, I couldn't do it.
[doublepost=1457800694][/doublepost]Never mind, I was able to gain access to my showtime account via a password reset using the apple ID. Still no success, even after removing all Apple TVs from the device list. I guess there's just something wrong with the Apple TV 4 Showtime app.