In iTunes, when I try to open a movie, I just get a black screen. A couple times, I've had a dialogue box pop up saying "The selected movie won't play on your display. This movie can be played only on displays that support HDCP.” I have a 2017 15" MacBook Pro, so my hardware should be more than sufficient. I've tried doing a PRAM reset, SMC reset, and even reinstalled Mojave. Any other ideas?