Seen this issue posted a couple of times but the solutions are either temporary or don't work for me.
I had an issue with this on my old TiVo, so an engineer diagnosed a problem with the box, sent me a new box and the same issue happens.
Every now and again my YouTube app stops playing the videos. Sound comes out but the video does not play. I also find that Netflix and Amazon doesn't play videos or sound during this time.
I go through the rigmorol of resetting the TiVo box with the thumb down last channel piece. Loads up after about 5 minutes and back to normal, but surely there can be something that means I don't need to do this? Clearing Cache doesn't work. I'm having to do this every day.
Re: YouTube and other TV apps not working correctly.
Sorry to hear about the Apps issue when trying to watch them on your TV Box. If the new box is having problems like the old TV Box, it may be an issue with it's internet connection. Can you tell us whether it's set up using a wired or wireless connection?
Can you also check the network settings on the TV Box by going to Home - settings - Network - View Network Status or you can run diagnostics by selecting View Network Diagnostics? What does it say?