Many issues here using ATV 4k, including all the remote issues mentioned above. Our big problem was the app would crash under the following conditions: BT connected milestone footpod, selected running, choose “training” in the top menu to access the workout menu. Upon attempting to scroll from the top level to any of the workouts, the app would crash. I switched to “ride”, connected my Kick’r, saved a short ride, disconnected the Kick’r, reconnected the footpod on the run side and it started working. Time will tell if this actually made a difference, but so far so good.
As for the remote issues - as others have mentioned - the remote sucks with Zwift. So I downloaded the Apple TV Remote app from the Apple store to my iPhone 6s and the app works way better in Zwift than the supplied ATV remote.
Next I’d like to see a custom workout builder for the run side.