There can be many problems with a display calibration process.
Color instruments vary in accuracy. When I received my PR
-670 it had calculation errors in it. I worked with Photo Research to correct this. Even very expensive tools ($24,000) can be wrong. They also require understanding to use properly. I can get bad results from mine by using the default settings in the product. You must know how to use it to get accurate results.
Color instrument error increases as the light level falls. I see many display calibrations that completely fall apart in the mid tone and near black region because of this. I developed my own tools to deal with this on projectors. When you get in the mesopic region for color there is no good way to measure it relative to what an individual sees.
No color meter is close to 10 bit precision. This makes very detailed color correction impossible with a light meter. The detailed corrections must be done at the factory through an understanding of the physics of the device and mathematics coupled with an astute use of color meters.
The software and test material you are using can also be flawed. I have seen zero automatic video calibrations in the home setting that are close. Each product is different in how the controls function.
Many of the color controls in consumer displays are defective in ways that are not expected. You have to be crazy careful to avoid these issues. For example, some displays will alter color gamut with gamma changes. Others will induce loss of bit depth when you alter the color management or white balance in a certain way.
These are just some of the reasons I recommended my post production clients purchase Sony BVM and PVM monitors. These are exceptionally accurate from the factory and avoid the errors introduced by calibration outside of the factory. I also recommend Christie projectors because their calibration process uses quality mathematics with the proper method for in-house calibration. This level of quality and precision does not exist in any consumer product.
Layering a LUT or video processor in the system does not remove the challenges you will face on achieving very high levels of precision and accuracy.
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