I have the V2 box and it's temperamental. I did get it to work on my 4K HDR tv (X900E) however at first it was coming up as some weird signal and every time I went to the ps menu the tv would switch away to another input. It's worse on my old 1080p tv where I don't get a picture at all, HDCP handshake fails when playing a 4K HDR game, it doesn't switch back to 1080p correctly.
It's definitely a HDCP handshake problem. What you can try is boot in safe mode and go to HDCP and switch it to 1.4 or off. Only if you do that you won't be able to watch 60fps 4K UHD with DRM. So that probably won't solve your 4K you tube problem... It did fix my problem with the auto input switching and random black screens I had earlier with the ps4 pro in 4K HDR.