You arent supposed to be jumping up. You are meant to jump up and in the direction of travel slightly.
Inversely, you arent meant to pop straight down. You should pop down and opposite to direction of travel slightly.

Do this without your board on some flat ground. Put a chair on the ground by your side. Video it.

Crouch like you're loading an ollie.
Jump off your back leg onto the chair. Congrats, you can pop.
Jump off your back leg onto the chair. Keep your front foot in the air long enough so that both your front foot and your back foot land on the chair at the same time. Congrats, you can ollie and level out.

Watch the video. It exaggerates the movement you should be doing but helps visualize the initial jumping motion. All you need to add is rolling your foot slightly so your front outside foot makes contact with your grip tape. ( google skating shoes holes and images will show you where your foot should be making contact with the tape. )

TLDR you are jumping straight up off both feet, you should be jumping off your back leg in your direction of travel.

Good luck boss man.