Have a look at a clipboard made a few years back all in slow motion.
The first thing I noticed is that your top half is rigid and doesn't really extend during the launch. If you extended your arms fully , then you almost don't need line tension to twist as you can tuck your legs and twist and add the shoulder. As you approach inverted naturally rather than forcibly.
The board plays a massive role in how you get the pop, generally big fat tips are better at holding edges and stomping to flip up, if your mid sections are much bigger than the tips, you will loose edging ability when you stomp, or if your board is good at carving ( rounded ) , requiring more speed, higher kite angle to pull you up as pop is reduced, and more line tension, will give you more steering.
Check out the clip u can see which boards give you troubles stomp popping. I'm about halfway on a stiff aboard, and need speed and kite position to get off .
Find square, flexy tips, stiffer mid the best