I’m new to Astropad, just bought an iPad Pro 9.7" yesterday. I like to share this issue I faced today.
When you have “Zoom” switched on in “Accessibility”, Astropad (or the iPad??) gets lost occasionally. The screen is zoomed in at the maximum zoom level and the screen locked, you only can see the middle of the different screens. It was a little bit of a struggle to find what caused the problem and to find the settings icon on the zoomed and on locked part of the screen, to switch of “Zoom”.
So the best thing to do I think is: switch of "Zoom’ before you start Astropad.