If you are experiencing a black screen while trying to calibrate the video crosshair in the new ShotKam App, then please check your iPhone's iOS. To do so, please follow these steps from Apple: Find your software version.
We have found that the black screen issue is stemming from iOS version 14.8.1. If you are experiencing the black screen issue and have iOS 14.8.1, then please update your iOS to iOS 15 or newer. Once you have updated to iOS 15, then follow these instructions to Calibrate the video crosshair.