I have bought dell xps15 7590 few months ago. it is connect to a 4k tv via hdmi. I just use 4k tv and the primary laptop display screen is off most of the time.
However, when I turn on my laptop with tv connected to it via hdmi, the tv display becomes all grey/black. Then if i disconnect hdmi cable, the primary display of laptop won't turn ON. The laptop is ON, fans running and keyboard backlight also on. however its display will be off. The only way for me to fix it is press and hold power button with hdmi disconnected and reboot laptop. Once laptop is ON then connect hdmi.
This works only sometimes.
Another problem is, if laptop goes to sleep and i have opened some files i was working on with tv as a display. then it is impossible to bring back the files because i will have to reset the laptop to fix the screen. I have spent hours on dell customer care but no luck.
This is a serious issue for me because this also happens sometimes randomly when i am working. laptop freezes with no display on tv and/or primary laptop display.