I'm curious as well, anyone?Has the 4K and 4K/10 bit setting been discussed yet? I looked through some previous posts on this thread but haven't seen anything. My LG 65UF8500 won't sync with the 4K/10 bit signal from the ROKU 4 even though I enabled deep color on my LG. I think the problem may be that the LG needs a 3480x2160/50 Hz signal and the ROKU 4 probably does a 60 HZ(?).
On the initial set up with the ROKU not being recognized as HDCP 2.2 Compliant - I had this happen but once you do the initial set up you just need to go back to the settings display menu and it will then accept the 4K.
I had to return my ROKU 4 for replacement yesterday for another problem - finder locator wouldn't work plus remote was acting real squirelly.