At first try another HDMI cable and another TV or monitor to isolate the laptop as the culprit.
There is a brand new BIOS for your rig at ASUS ZenBook Pro UX550VD BIOS & FIRMWARE| Laptops | ASUS USA with an obscure desciption that might help
Optimize system performance
As usual BIOS flashing is at your own risk
Ask at ASUS' Notebooks forum if you need help with that.
I regretfully don't have a spare monitor that works on HDMI. But my other laptop works perfectly with this HDMI cable and this monitor and before I updated Windows 10 to the Fall Creators (1709) it also worked. I also just noticed that the monitor works up until windows starts. So when restarting my laptop, I do see the ASUS startup logo but then it freezes on my monitor while on my laptop screen I do see the windows login screen and am able to login but all of this doesn't appear on the monitor. When I then pull the HDMI cable from my laptop and insert it again I keep seeing this ASUS logo on the monitor.
The driver version I am using:
I managed to get my monitor working by downgrading to version: 18.104.22.16827