rear shock losing all air when I unscrew the shock pump. what am I doing wrong?

shock is a marzocchi bomber air rear shock, shock pump is a specialized air tool shock pump. I’m starting with the top screw completely loosened, then I tighten the bottom screw into the schrader valve, and then the top screw. after, I pump air into the shock, then loosen the top screw and then loosen the bottom screw. when I loosen the bottom screw, all of the air comes out of the rear shock. I know its not a stuck schrader valve cause I already tried pulling it with needlenose pliers and it wouldn’t budge. I’ve tried a variety of combinations of leaving the top screw unscrewed or keeping it tightened and none make a difference. I know I only pumped the shock up to 60 psi in the video, that was just for demonstrating without taking forever. I hope I’m just making a stupid mistake. thanks for helping, if you have any questions I can answer them

I was equally as skeptical, but this would just be the air escaping from the hose, not the shock.

The problem is that when you hook up the shock again to confirm the air pressure, it will inflate the hose again which adds volume and makes it seem like it was under pressure.

This is why sag rather than pressure is the best way to ensure your shock is pumped up correctly.