I can check that but I think that's the issue. The output voltage is not changing when pressing the keyboard direction buttons. I'm a mechanical person so when I encounter electronic problems I struggle.
I don't think Mach3 is the problem. The more I think about it's wiring or BoB related.
Problem solved! It was a wiring issue. I removed the Enable - wire from the BoB and the motors moved as expected. What's interesting is I wired the motors, drivers and power supply the same as my mill when I was using this same BoB and UC100. Must be a difference in the driver internals between my mill and lathe.