Welcome to the forum.
I have had similar problems when I stepped over the USB cable recently. I had been using a crowbar to hold the metal down on the table. Perhaps the crowbar or I got some electric charge and when stepping over the cable it seemed to interrupt the signal. In this case, the torch kept burning but not moving and FireControl was continuing on with the pattern.
It sounds like some electrical interference with you.
Another thing could be the air pressure dropped down and the torch turned off. What plasma cutter are you using and how is it wired?
Some time ago (2 years), I was cutting aluminum. Aluminum flecks were going everywhere. The next thing I cut was steel but I didn’t bother to check the consumables. There were times it was cutting perfect and others that it was just scratching the surface. It turned out that there were several little pieces of aluminum that were trapped up in the torch. But the torch was burning the whole time and it was following the pattern.
Last example: I had a stepping issue recently (same project when I was using the crowbar). Everything was cutting perfectly and then I started losing steps with the y movement. The caused the new cutting to be on top of some previous cut areas. I blame that on my computer being low on battery and possibly re-allocating CPU focus away from the USB cable. I plugged the laptop in and re-cut without a problem.
I can’t really tell from this description:
whether you are saying it followed the expected pattern or just skipped an area and went to a new area. In either case I would say something interfered with the signal from the computer.
It could be your computer. Does this describe your CPU?: