A while back I was trying to use our YouTube app on the Virgin hub, the video was playing sound but the picture was blank. It was very infuriating as we’d only used it a day or so before so not sure what had changed. Tried troubleshooting advice online and nothing worked so resigned to the fact that we didn’t really need to use YouTube. Today I’ve gone to watch something on the BBC iPlayer app that I have also used before with no issues and the same thing - just sound with a blank screen. How do I fix this?