Restarting in line fail, while using Mach

So I’m cutting a complicated sign and burn a plasma tip. I pause (spacebar), change tip, back the code up, and restart.
This has worked a couple times, and failed a couple times.
When I restarted Mach, the torch fired and the cutter ran diagonally across my part. Why? What did I do wrong?

Another time, torch went slo-mo and did a big 360 before returning back to normal.

What is a safe line to restart on?

What do you use to generate the toolpaths/code?

Fusion 360. Pretty sure I’m telling it to restart at the wrong time.