so on my nx2's, I have been working with the guys in customer support to help me dial them in. One thing i found was that one of the screws was too tight where the ladder strip (sorry for bad terminology) connects to the heel cup, if you have the black version it is the part with the white cap. I found that when I pulled my back open, the ankle strap was being pulled to down to the right instead of lifting up as it should. I was able to fix that by loosening the screw and re tightening them. what was happening to me was that i was constantly adjusting the strap, since the system was not working smoothly.
I called the guys at flow, and they are very helpful. they have spent countless hours on the phone with me and in email, trying to help me dial these in. They really do have the patience of a saint. as I am new to snowboarding and need a lot of hand holding to dial these in.
I have not had a chance to get out to the mountain to try out my tweaks in the wild, but am hopeful