Astrophotography experience

I haven't had very much luck with astrophotography, and there is something that happens that makes me question whether its an issue with me or a problem with a sensor or something.

All that to say, I haven't had an opportunity to test with a tripod.

What happens:

I can take a pic with astrophotography, and then when I tap the image preview thumbnail, it loads, and I see tons of stars and it looks awesome, but only for 1 split second, and then it's like it does some auto adjustment, and it changes and then it's really dark and I can hardly see any stars. It's kinda hard to describe. Anyone having similar problems?