[jpik]

If you have deep color on, you will get black screen (AV dropouts) at 2160p. To prevent this you can either select 4:2:2 or turn deep color off at 2160p.

4:2:2 output can only be 12-bit as per HDMI specs. If you set it to 10-bit, on reboot there will be no video output.

4:2:0 is allowed only for 50/59.94/60Hz at 2160p as per HDMI 2.0 specs. If you select 3840x2160/4096x2160 50/60Hz, you will see 4:2:0 as an option.

Thank you, for your explanation. I forgot to take the interface into Account.

I have found the following on hdmi.org:

It seems that for 4K movies (like the one on HD Blu Ray) 4:4:4 is the best output format. But in this format the screen goes black every few secounds.
Futhermore i don't see a deep colour output when set to 4:2:2 and 12 Bit (as HDMI) allows.
So currently it is not possible to see 4K/HEVC/23.976/10 Bit. I used Spears and Munsil Quantization test video and other sources.