Mobile 5.4.0b14 - Black Screen on some iOS devices

After upgrading our game from b3 to b12 (also tried b14 with same result) we are facing this problem:
When starting the app a black screen appears directly after the custom Launch Screen of Unity.
The game seems to be running normally in the background (you can hear all the sounds and you can play) but you can not see anything.
This only occurs on these specific devices:
iPhone 6S (iOS 9.2)
iPad Mini 2 Retina (iOS 8.1.2)
iPad 3 (iOS 8.1.1 & 9)
iPad Pro (iOS 9.1)
On all other devices we have tested the game is running just fine.
Is this already a known issue or do you have any solution on how to fix it?

 

After further investigation we finally found the cause of this problem:
We were using Screen.SetResolution to change the resolution for all low spec retina devices.
Apparently this command line is not working anymore with the new beta versions which seems like a bug!

 

Bug report # please so we can track and investigate?

 

Bug report:
https://fogbugz.unity3d.com/default.asp?789916_gisbukf2ghj53bpb