This is in response to the following Thread.

Topic: Probe calibration error
https://www.machsupport.com/forum/index.php?topic=44931.0

The solution in the initial post was to alter some Lua code, which only partially worked for me.

I think I found a better solution in the Warp9 documentation. Hopefully it helps somebody because it certainly stumped me for the better part of a weekend.

Warp9 Documentation:
Probing in Mach4
http://documentation.warp9td.com/Shared/Mach4/Probing/Probing.htm#:~:text=ESS%20%3E%20Software%20Mach4%20%3E%20Probing%20in%20Mach4%20

About half-way down the document under "The Probing Config Tab" header is the solution that worked for me.

Here's the gist of it.

In the ESS configuration window under the "Probing" tab you just uncheck "Probe Failure Disables Mach". Then run the calibration sequences and be sure to turn "Probe Failure Disables Mach" back on when you're done.

I don't know if it's a particularly safe solution, but it worked.