I have had issues with SBS ondemand app and ABC iView that have some commonality:
SBS ondemand has a tendency to stop after a few minutes (goes back to show/episode launch screen). That said, I have long had issues with the app on iOS with it seeming to get stuck in the transition from ad back into tv show/movie. I have noticed this starting to happen on tvOS following the recent update.
ABC iView seems to put tvOS to sleep after a few minutes (atv goes to screensaver).
Without actually measuring, the amount of time for both seems similar... Something changed in tvOS?