Images used in Relative & Constant launch screens aren't included in the generated Xcode build, resulting in the Xcode build failing

Steps to reproduce:

1. Open attached project (splash-test.zip)
2. Switch to iOS platform
3. Make sure that 'Unity Launch Screens' are set up with the included images (Player Settings/Splash Image)
4. Build for iOS
5. Open the generated Xcode project and try to build via Xcode

Expected result: Launch screen images are included in Xcode project, the build succeeds and the image is displayed on device.
Actual result: Launch screen images are missing & building via Xcode fails because of that.

Note: Same happens with relative and constant launch screens (as stated in the title). Using 'Default' launch screen does include the default, black-ish images in the resulting build.

Reproduced with: 2023.2.0b3
Not reproducible with: 2022.3.5f1