I kept a close eye on my cam.
I don't think there's a problem of sometimes not auto starting after all... I had the ignition on, the camera started, I turned ignition off, after 2 mins I restarted,
The camera came on... then the screen went black, I waited longer than I have done,.. about 30 seconds it came back on with a padlock in the centre, that video disappeared and reverted back to normal with the screen on.
I also noticed when the screensaver mph is on and I come to a halt and my engine stops ( the engine has isg) the screen comes on, then after 30 seconds it reverts to screen saver.
I personally thinks there's nothing wrong.
I hope this makes sense.