Default UE splash logo appears briefly when launching an application with an alternate launch image on iOS

Various users have reported seeing the default UE splash logo appear briefly before their custom launch screen appears. This was reported to have been seen in 4.25, and did not occur for users in 4.23 or 4.24.

This issue has not been seen on Android

Users have reported seeing this issue on iPhone Xs and iPhone 8. Issue was tested on an iPhone 6S, and the issue did not occur.

This issue was not reproduced locally when tested in 4.25.3 with a First Person blueprint template project set to Shipping configuration on an iPhone 11 when deploying manually to the device and 'For Distribution' unchecked. It is possible this issue is specific to deploying the application to the device via TestFlight.

Repro steps from user:

1. Open any project
2. In Project Settings > IOS > Launch Screen, set Launch Screen Image to any alternate image
3. In Project Settings > Project > Packaging, set For Distribution to True
4. In File > Package Project, set build configuration to Shipping
5. Package for iOS
6. Upload to Testflight with Application Loader
7. Open application on the iOS device

Results: UE4 splash screen logo flashes briefly before the alternate launch image appears