`Validate Nozzle N1's Offset` makes nozzle crash into the datum

[EG-Julien]

Hello,
I was re-installing openpnp and while following the calibration docs, the Validate Nozzle N1's Offset step 2 with a Z at zero makes the nozzle crash into the datum board.

I started over the nozzle offset calibration making sure that I have checked 'include Z' but got the same result ... If I manually jog the nozzle to barely touch the datum board and I got Z = 15.000.

Did I miss something ?

Thanks