Thanks for the feedback Shadowspectre and felipe.
I think my issue is that I’m not popping up the yoyo in a controlled or consistent manner.
No, I don’t know the thumb grind yet. Should I learn the thumb grind before this?
Also, I am aware I need to keep my finger bent…
When I finger or palm grind I pop it up to the same height-velocity-orientation every time. I’m thinking I need to bring that uniformity to this trick.