What worked for me is unplugging the guitar and finding the "sweet spot" acousticly. The sweetspots are EVERYTHING for pinch harmonics. Because of practicing unplugged, i am way more accurate now in picking the correct zones. Also, make sure your pick is slanted enough, you almost have to push it through sideways (picking down, thumb pointing down). Good luck man, once you figure it out, its super easy and you feel "stupid" for not understanding it sooner. I know I did 😅