To reproduce:
1. Open users attached project "OrientationBug.zip"
2. Build for iOS
3. Open the Xcode project and deploy it to an iOS device
4. On the device press "Button" button to change screen orientation using Screen.orientation = ScreenOrientation.LandscapeLeft;
5. Observe as the screen looks upscaled and the cube is not visible anymore

Reproduced on:
2017.3.0p2 2017.4.8f1 2018.1.9f1 2018.2.2f1

Not reproduced on:
2017.2.3p3 2017.3.0p1 2018.3.0a1 2018.3.0a6

Notes:
If you rotate the device to landscape mode without pressing the button, the orientation changes without any issues

Device reproduced on:
iPhone 7 iOS 11.0