Also, if it was only happening in the Ki84, turn OFF combat trim. You cannot pull enough Gs to black out with it enabled, most times.
After calibrating, go to the stick mapping setup page, choose each axis, and click the "advanced" tab. Make sure that axis gets full deflection.
You can calibrate in AH and still not get it right. If that happens, you have to exit AH, calibrate in windows (and test in windows) then go in and recalibrate in AH.
Every time I lose power, don't shut down properly, whatever, I have to recalibrate in windows. I use gameport controls. USB might not have the same problem.