Please try giving launch images with your ipa. For iPad Pro, you need to add below launch images with dimension as:
Default-Portrait@2x.png : 2048 x 2732
Default-Landscape@2x.png : 2732 x 2048
Let us know if it resolves your problem.
Adobe AIR Team
It dawned on me now...
The launch image is defining the resolution of the app it self. I did not understand why other threads online was changing the subject from resolution to the launch image before now.
Can confirm that it works now 🙂