LG 55B6V - How to watch HDR on PC?

hi all 🙂

so I am really frustrated. bought myself this stunning oled panel, and after two weeks I still havent seen a glimpse of hdr picture.

I am trying to watch 10bit HEVC movies on Win8.1 pro. in 1080p.

I installed the latest updates for the TV
I use bright room expert color profile and enabled Deep Color on my HDMI.
I tried HEVC 10bit material on a strick directly on the TV. it shows "HEVC" but no "HDR Material" message appears on the screen
I tried all the HDMI ports, disabled and enabled deep color on them
I bought a new super fancy HDMI 2.0 cable. (I think it's not nescessary, but I wanted to rule it out as the error)
I switched the HDMI input logo to PC (does the tv treat signals in another way if you change the image?)
I have GTX970 but now also tried a GTX1060, all with the latest drivers

I tried using MPC with LAV or madVR decoders.
CTRL+J tells me that the signal is 4:2:2@10bit when I switch to fullscreen, but it looks like normal 8bpc, and no HDR message on the TV either.

So help me, what could be wrong?

Cheers