I’m going to caution you against ordering a new bitzero to rectify this problem. If your probe light is turning red, and z-axis is retracting after a touch-off, the probe itself sounds like it’s working right. The probe isn’t performing any mysterious calculation, it’s merely completing a circuit and letting carbide motion know that your bit has come into contact with it, and carbide motion knows that if you’ve set it up correctly, the bit has completed a circuit exactly xx.x mm above your workpiece.
I don’t know if you answered my previous question, when you set probe on surface, and probe “Z-only” does your job run properly?
On one of these air start jobs, have you allowed it run to completion, and see where you finish off?
Can you elaborate on your steps?
What bit are you using?
Have you double checked that your file isn’t set to a stock bottom-zero?
Triple checked that you don’t have an erroneous stock thickness entered in CC?
If you’re using belt drive Z, have you checked your set screws on that?
Are you using a bitsetter in combination with the bitzero?