It sounds like youre tapping a little too early...
I would have to see it... from my understanding of it.. you want to push the bar away from your as much as you can, keeping a tall extended hollow, and before you reach the bottom you tap.
Ride the swing, and pull down on the bar. On the straps, you have "zero" friction - you dont have to worry about turning your hands because they are turned for you through the motion. On the real bar, you need to feel yourself rising and have pressure on the bar before you shift.
As Previously suggested, work reverse grip back-uprises and get them higher and higher. It will help in the long run.