So, it worked fine for a while, and then started going backwards?
Did anything change in your system?
Do you by chance have a CNC Drive pendant? A small number of people with these pendants have had issues with the probing macros.
I don't believe I've ever heard of this happening to anyone.
The way the probing works, is the macro first reads the Z axis DRO. It then subtracts the Firs Probe Distance, and tells the machine to probe to that position. So it should always probe downwards.
When it's moving up, is the Z axis DRO value increasing?
Do you ever have any other issues with Z axis direction? A bad connection on the Z axis dir wire could possibly cause this.
Can you post a screenshot of the Auto Zero settings, and the run screen DRO's when you start to probe?