@TerryRitchie Remember, when _DISPLAY isn't used, _AUTODISPLAY is the default.
What you're seeing is AutoDisplay triggering _Display, pushing the hardware image onto the screen, and then flushing it from memory. The next loop around, AutoDisplay triggers _Display, but there's no hardware image to sync and push with now. That's where the very, very brief display you're seeing is coming from.
Hardware images won't render without a call to _DISPLAY, but it doesn't matter if you do that call or if AutoDisplay does for you.
What you're seeing is AutoDisplay triggering _Display, pushing the hardware image onto the screen, and then flushing it from memory. The next loop around, AutoDisplay triggers _Display, but there's no hardware image to sync and push with now. That's where the very, very brief display you're seeing is coming from.
Hardware images won't render without a call to _DISPLAY, but it doesn't matter if you do that call or if AutoDisplay does for you.