Thank you for joining the Intel communities.
I never heard this problem before when using a display port connection, what I can offer you is the latest graphics driver, you can download it here:
Just today Microsoft released the newest firmware and new display drivers were included jn the package. Problem is still there.
Closing as HW issue - Single Unit Failure
My case turned out to be something wrong with my Surface. I today tried with another one (the same as mine) and the monitor works like magic. Obviously something in my port or something that's next to it inside the tablet itself is broken / damaged / whatever...