What would cause my launch screen image to be black for the few first seconds on iOS?

I have a launch screen image set for iPhones and iPads. When my iPad starts, it shows the launch screen with its white background, but my launch screen image is initially a black box for a couple of seconds, before properly showing the image.

Here are the launch screen image's import settings:



What would cause this behavior?

Thank you.

 

I had this issue. Also it seemed to occur on some builds but not others, without changing anything to do with these textures or build settings. One thing I did which I think solved it (because I've not seen the issue since doing this) is to add each of the images (LaunchScreen-iPad, LaunchScreen-iPhoneLandscape, LaunchScreen-iPhonePortrait) to my images xcassets file within xCode. They are just there as Universal 1x