I cannot get 4k (3840×2160) output to work at all on my Surface Book, either with or without the Surface Dock. I have a Panasonic TC-55CX420U 4k TV that support HDMI 2.0, all the inputs on the TV have been configured to use an HDMI 2.0 link (vs the default 1.4 link). I am using a Zakix 6 ft certified HDMI 2.0b cable and the official MS Surface mini-dp to HDMI adapter and I am trying to extend the displays not mirror them. Unfortunately the highest mode I can select for the external monitor is 1920x1080@60Hz... I should be able to select 3840×2160@60Hz but no dice. And I have tried this with the mini-dp to HDMI adapter connected both through the official Surface Dock and directly to the keyboard section, no difference in behavior.
I have tried unplugging, replugging, rebooting, and powercycling the components in every permutation possible. I have also tried uninstalling and reinstalling all the drivers, I even tried a complete reformat and reinstall of windows 10. And according the windows update my system is completely up to date. But still no 4k option!!
Here is the REAL head scratcher though... previously I COULD output 4k resolution using an after market mini-dp to HDMI adapter but I could not get audio over HDMI to work with it (never showed up under playback devices, impossible to set HDMI as audio output), that is why I ordered the official microsoft surface mini-dp to HDMI adapter. When I plugged in the official adapter, I immediately got audio over HDMI working, but now it wouldn't let me select higher than 1080p! So then I tried swapping back in the old aftermarket adapter, and it now has the exact same problem! No 4k on either adapter now!
At least audio over HDMI works now >_< this surface book has been nothing but a nightmare of problems since I got it.
