Find your maximum RGB levels using the sensor - decrease two of the colors to track down to D65. No need to use the software to tell you what to change next if you learn your color science on how colors add/subtract. You should be able to calibrate without the RGB histogram or bars visible - just use the D65 target. You will get better results than relying on dancing bars to tell you what to do. There are infinite RGB combinations that will give you a RGB D65 balance - only one of the combinations gives you maximum contrast with targeted gamma.
Usually red is your limiting color with UHP and blue with Xenon - but that is not always the case - depends on firmware, gamma, clean optics....so do not assume anything.