If your device is a firestick, a recent Amazon update has required the ‘Still Watching?’ setting to be turned off. If this setting is left on, a firestick will play happily for a set period (usually 4 hours) but will then pop up a message asking if you are ‘still watching?’. Without a response the firestick will shutdown AbleSign and revert to the home screen.
AbleSign does not modify your original uploaded file so you should be sure your device is capable of playing it. In particular, entry level devices such as the Firestick Lite may struggle with demanding playlists that include videos encoded at higher bitrates and very high resolution images.
HDMI CEC device control
Some commercial displays with timers use CEC device control which can cause problems. It is best to disable this feature. For a Firestick this is in settings -> Display & Audio -> HDMI CEC Device Control.