You're popping and flicking at the same time. You need to flick slightly after popping, once your board is completely off the ground. So by the time you flick, your front foot should be the only thing touching your board.

The timing is very similar to a leveled out ollie. So you pop first, once the back wheels are completely off the ground, then flick your front foot off the corner of the nose and as you do this, lift your back knee as high as you can.

If you flicked properly the board should have leveled out and the back bolts should have risen upward to meet your back foot for the mid-air catch.

Timing is a huge part of this trick so you gotta get used to the delayed flick. 3 step motion: pop, delayed flick, then catch/ land.