I am generally what one would consider an intelligent person in most respects (university professor doing research in STEM involving plenty of math, etc.) but for some reason, I am totally unable to understand how this technique works.

I can follow the instructions, I know that it works, and I have a vague, superficial idea of why it's plausible for it to work (something like "things are inverted twice so it turns out OK") but I am unable to make a mental model of exactly how and why it works.

I find this quite annoying because it also makes me forget the technique every time (typically I remember things because I understand them, and I don't understand this... for me, the correct way to do it is equally plausible as other alternatives, so I forget the correct steps). I do it together with my wife and she always has to give me detailed step-by-step instructions as if I were a kid, and I think she thinks I'm trolling her because for her it's obvious, but I'm not trolling.

It's funny how one's mind can have weaknesses of this kind. (Related to the same weakness, I also get confused and spend a few seconds thinking when a sweater has its sleeves outside in or when I have to recover something from a coat pocket with the coat hanging, sometimes I actually put on the coat to avoid thinking about where the pocket is, but the duvet replacing thing is the most extreme manifestation because not even by stopping and thinking can I understand how it works).