Steps to reproduce:

1. Open attached project (test-storyboard-error.zip)
2. Make sure that these Player Settings are set as follows:
- Resolution and Presentation/Requires Fullscreen is disabled
- Splash Image/Use Storyboard for Launch Screen is enabled and test.storyboard is selected
3. Build for iOS
4. Archive the Xcode project
5. When the app is archived, select the build and click 'Validate App' in the organizer window

Actual result: App validation will fail because Xcode fails to find the specified launch screen value.

Workaround: Removing .storyboard extension from the Info.plist "UILaunchStoryboardName" value

Reproduced with: 2018.4.24f1, 2019.4.3f1, 2020.1.0b12
Not reproducible with: 2020.2.0a16 (was fixed by moving 'Use Storyboard for Launch Screen' option to the Launch Screen type dropdown)