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.
I hot it working. My setup is the PS4 pro cable running from the PS4 to the breakout box and the my 18gps cable running from the box to the TV and as someone said above, I turned on setting on the TV which allows "ultra deep colour". I also had to turn on a similar setting on the PRO. The only game that doesn't work is The Witcher 3 but that also doesn't work with my expensive hdmi cable directly, I just get a glitched out screen with washed out contrast in blotches. Pity too cause that was one of the titles I bought the TV for.
Everything in the above reply is my opinion, from my own perspective and not representative of reality outside of my own head!
-Android user, please be gentle with critique on my spelling.