That's the thing, I'm claiming that the implementation I tried DID work. Now, questionable YouTube videos, however, haven't worked for me before. Nor do the settings in the software for my discrete sound card. But I have experienced it with one particular company's implementation.
What was explained to me is that they have a generic HRTF that works for ~90% of the population, but there's a minority of the population for which a customized HRTF must be determined. They claimed that certain differences in the spatial characteristics result in their generic HRTF not being a good fit; perhaps you are part of that unlucky 10% who would need to be measured in a lab.
This was actually the topic of one of the questions I asked of the presenters, and their answer was to concede that unfortunately those 10% would be out of luck unless they got their personal HRTF derived. Who knows if the numbers are real or not.
Sorry you're getting downvoted for having a dissenting opinion/experience.