I don’t need a fix (the job came out great) but is essentially a bug report? I didn’t just want to append it to the thread in the snap marks discussion as wanted someone to be sure to see it.
I was doing slate name cards so decided to use SnapMarks. So then I cut the jig in 
medium draftboard and scored the snapmarks on. The onscreen preview was way off alignment-wise before pressing the magnet button. Anyway the problem I ran into was that the job threw an error that there weren’t enough snap marks in the job to work (there were 2), but after throwing that error it clearly aligned itself to the snapmarks so not sure what that meant, so it came out great (as you can see clearly aligned)
Here is the source file if that matters:
passover slate jig 2019 - 1.svg.zip (8.2 KB)