This must happen to other players too. It has happened to me many times. I learn a trick and can do it at least somewhat proficiently for a long time. But one day I just cannot do it, as much as I try. And it has happened to me even with tricks I created
Even if I can watch videos of myself doing it . . . It is the most frustrating thing!
For example, yesterday I could not do half-orbits, a trick I learned over an year ago. It took me a while today to get it back. And now I need to "remember" how to do the upside-down corkscrew . . .
The good thing about these lapses is that many times it helps me realize that something I did automatically is important or learn something else about the trick so at the end I do the trick better. But it is so damn frustrating!