I'm using Xamarin Forms to create iOS app. Only on iOS 11 the app splash screen has a black box in middle instead of an image. I don't know if it is related but this issue started to appear when we changed language on phone to test localisation. I'm using LaunchScreen.storyboard to create my splash screen that comes with Xamarin Forms sample project. Also if I change the image name in LaunchScreen.storyboard the splash screen starts to appear right for a limited time.
I'm using latest VS 2017 15.7.2 and Latest Xcode
In my case, my image for the splash screen was on resource (not assets) folder as a png file.
In the splashScreen widget, changing the name of image without extension (my_image.png -> my_image) worked for me.