@fcwilt yes, that's what I have to do,
I'm wondering why it doesn't work the way it's supposed to though?

@fcwilt ok, a bit over my head, but the probe height is entered first per the instructions provided by the machine maker, then the z height.
Point is I get a difference number that I enter, but it's as if the machine ignores it.

Our workaround is to start a print, then stop it, and measure the height of the nozzle from the bed. We then change the z offset by that amount, minus the .3mm we need to be from the bed. It works, but it's not right and would like it to work properly.

We are using a Modix 3D printer with the Duet 2 Ethernet board.
I am following the set up instructions on the Modix site.
I touch off the BL touch sensor, then touch off z offer calibration (using a price of folded paper between the nozzle and the bed).
At that point I'm given a number to enter in the G31 line for the z offset (which should be the difference between where the BL Touch probe triggers and the tip of the nozzle, as I understand it).
When I run a print, the nozzle is way too far from the bed to make a print, usually around 2.5 mm rather than the .3mm that it should be.
The people at Hartsmart who sold the machine, so far have no answers.
Can anyone here figure out what might be wrong?