Screenshots showing up black when watching Apple TV

So, I’m watching the new wolfwalkers movie Apple TV released today (12/11/2020), I’m trying to take a screenshot of the movie at the timeframe 51:41 because I want to use it as my wallpaper, but when I do, it shows up black, but when I retake it with the scrubbing bar showing, the movie is black but the bottom bar shows, why does this happen and how can this be fixed? I’m on a iPhone SE running iOS 14.0.