ok, I think I figured this out.
My problem was not the colorimeter, I got similar results with the spec. It's unlikely both devices are defective, so here is the conclusion. I have this problem for 3 reasons:
1 - Sometimes if dispcalgui was already used previously, it will load an old calibration profile and mess up the new calibration. In order to avoid this, I recommend always clicking on the profile menu and changing it to "current", to ensure no old profile is loaded. If you run the tool with a profile loaded, your calibrations will drift towards yellow / red more and more for each subsequent calibration
2 - the test patterns will change from massive / large to a previously created patch set. you need to make sure you change it back to massive / large. this seems obvious, but I overlooked this detail in the middle of many tests / calibrations The issues above caused my calibration to never really reach D65. Once I got that nailed, it's very close now.
3 - Having your display previously calibrated (grayscale) makes a huge difference. Why?
Interesting enough, my whole workflow is set to 0-255. If I don't calibrate, my 255 white will be around 7100k, not 6500k. For some reason, madvr only applies the calibration to 16-255, anything above or below is not affected by the 3dlut. I believe this is by default, but the result is:
- when I watch a movie, everthing looks right. there is nothing white at 255, so my eyes adapt to 6500k and whites look white
- when I look at a white clipping pattern, the 255 white is at 7100k (due to my uncalibrated TV), and the 235 white is at 6500k. This makes the 235 look yellowish Since we don't watch patterns, in real life this has no effect, but if you want to avoid the issue with the WTW, the best solution is to pre-calibrate the display to be close to D65.@N3W813:
Is your display pre-calibrated? If yes, I guess that explains why you couldn't see the yellow bars :P