Hi, i think the problem most probably lies with the Onkyo receiver. Due to the NU8000 is using updated HDMI 2.0 function (i.e. ALLM, function from HDMI 2.1 spec), hence, the Onkyo is unable to process the video signal sometimes. See whether your Onkyo provide any firmware update to support the latest ALLM function.

I'm currently using the same TV model as you but with Denon X2300W with updated firmware (i.e. with ALLM fuction), so far so good with the Himedia Q10Pro plugged in.