Seems to be the case with me usually. “It’s on the tip of my tongue” then someone else spits it out and it’s not a word I’ve ever encountered in my life.

This seems like a poorly designed experiment to me. People providing partial information about a word that’s “on the tip of their tongue,” would be expected to make wrong guesses. If they could make the right guesses, then there are good odds that they would be able to reconstruct/recollect the word. You could just as easily interpret this as the word having been “misfiled” so that its recall is blocked by incorrect information associated with it.

I get TOT far more often than I would like, but there’s almost always a word that I get to eventually.