Today, many riders use the “ollie-pop” on more than just the flat-level surfaces in between other tricks, it’s used heavily in the half-pipe and bowl ramps to allow the rider to go even higher in the air. Performing the “ollie-pop” while you’re at or near the top of the lip is a great way to get an extra couple feet, which might be all you need to get that extra turn in and nail the 720 (or 900, if you’re Tony Hawk).
I found that my problem was unclear instruction about the timing between jumping and popping. One day when I was watching a slowmo ollie video though, I noticed that the skateboarder already was beginning to jump (at least his body was already going in an upward motion) before snapping the board off the ground. That was a critical change I needed to make in order to get it working. I had been trying to pop the board while all my weight was still pushing down on it (kind of an obvious mistake, but I somehow overlooked this). Hope this helps somebody.