So it looks like the new iPad Pro resolutions aren’t supported when using static launch images (which is what we add to iOS projects when re-saving in the Projucer) and we need to use a launch image storyboard instead.
I’ve pushed this commit which will add a default blank storyboard if no custom xcassets are specified, and also a field in the iOS exporter where you can specify the name of a custom storyboard you want to use (this file needs to be added as an Xcode resource in the project). This should mean that your app supports the latest resolutions and won’t have those black bars surrounding it.