Text example program, works ok, repeat program but cuts upside down, plus other error

Greetings all. I am a new Taig cnc and mach3 user. Today I tried out the taig cnc text engraving example code. It worked fine but I had a rough cut. So I decided to re-run the program to see if the finish would clear up. Worked ok again, but then I tried a third pass by rewinding the code and running the program again. Much to my surprise the text started from the usual start position but started to cut the text upside down! (mirrored).

I then had a go at cutting the ellipse program. Again all worked well, and out of curiosity, tried more passes. Second pass cut fine and from the same start position, but then when I tried to run the program again the machine attempted to start cutting the ellipse from a completely different position on the material, and not even on the same path as the previous passes.

How I got to this point: I started up the mach3 software and changed the units from mm to inches in the settings page so the text example code would cut at it's intended size (it is in inch units). Then I positioned the centre of the spindle centre on the material, and the cutter touching the material. From there, I zeroed all axis. With each example code (the text example and ellipse example) I ran the program with no issues, then rewound the program and executed the code again. I have changed no other settings in the software.

I am sure the stepper motors are not getting stuck but it seems like the code is not taking note of my zero settings and maybe suddenly deciding to use a different reference point.

What should I look for in the code and mach3 settings to troubleshoot this issue. It's a big problem potentially because as you can imagine in a production process you would want the machine to cut from the intended position every time without fail, especially if you are using a fixture to hold the workpiece.

:)

It's not normal to have the direction bits flip like that, and Mach3 normally remembers starting points. It sounds like something is corrupting your Mach3 settings as you're working, perhaps a grounding issue or some RFI. Have you experienced any other odd behavior from the computer you're using to run the Taig?