Okay, a few more questions.
What material are you cutting?
If this is metal and as you stated you're in inches, then plunging into the material at a feed rate of 20 seems a bit fast to me. Guess it depends on your horsepower.
Have you been successful in the past?
If so, what has changed with your machine?
Other than missing the G54 parameter in the posted code, I think you're possibly looking at a reinstall.
But, it seems your macros for the probing have gotten hosed up. Can you reinstall the macros? You might try that before doing a fresh installation of Mach3.
From looking at the code produced by Vectric it looks straight forward.