Fake Cuphead iOS App
Well, shame on me I guess. The Verge is reporting that the latest Cuphead app is a fake, which probably explains the issues on the iPhone X.
By the way, you can request a refund by going into iTunes on the Mac and viewing the order ID. Then click the “More” link next to the app and finally click the “Report a Problem” link under the app. Here are the instructions for doing it from your iOS device.