Hi Michael,
Thanks for reaching out to us, I am sorry the output is not as desired.
I have taken a look at the specifications of the monitor and it has support for 120Hz, if the computer is trying to output 4K @ 120Hz it may be shifting the chroma sub-sampling down to 4:2:2 or 4:2:0. I would recommend setting the monitor for 60Hz to attempt to rule out the 120Hz setting causing this problem. The 120Hz option should be under the “Settings -> TV picture settings” menu on the television.
After changing this setting, please disconnect and reconnect the adapter, if this does not resolve the chroma sub-sampling issue, please restart the computer to make sure the settings are re-detected.
Please let me know if this helps,
Thank you,
Pat
Plugable Technologies
www.plugable.com/support