Why does Apple TV app not stream video as well as iOS app?

I have a low-powered NAS hosting Plex, and I create optimized versions of shows I record. The iOS and Roku app will play anything I record from TV with no problem, but I’ve never gotten the Apple TV app to play these well. It usually just shows the spinning icon. Is this a bug?

We need some more info:

  1. NAS model
  2. Plex Media Server version
  3. Plex for Apple TV version
  4. Mediainfo (xml file) of one “problematic” film
  5. Is the AppleTV4 wifi connected ?

Thank you for the reply. The Apple TV seems to be doing better now after a few updates.