DTVS Gemini says my Samsung UN65KS8000 is not HDR compatible.

Just a thought, but have you tried a different HDMI cable? 

Yes I have changed it to a 4K HDMI cable and even changed the HDMI port

Did you solve this prob?  I have the same issue and  I’m on chat with an agent that’s going nowhere. 

@WendKend There is a setting on my Samsung RU7100 tv----"input signal plus" (settings---general--external device manager) needs to be turned on in order to enable HDR on the Directv Stream device. I don't have HDR enabled on my Samsung tv---pic looks better with it off and display set to 1080p. I think you enable the KS8000 HDR under picture settings--expert settings. 

Thank you!  I’ve done all that (input plus on/off, hdr on/off, changed ports, etc.). Still nada!  🤷🏼‍♀️ It’s aggravating that some of these settings don’t have an “auto” option. Anyway, life is too short—moving on!

@WendKend Unplug your tv from the power outlet for 60 seconds and also restart your Dtv Stream device.---Then try

I have that same TV but the curved version. To enable HDR you need to try the setting called HDMI UHD Color