Background lines with offset fill?

I did the material test in Lightburn and got the following result.

Then i did a test of six stars so i could see what line interval and overscan does. the bottom two stars are fill with no overscan, then next two are fill with overscan 2.5%, and the top two are offset fill. Non of the fill test worked. The offset fills had clean stars but there are route lines in the carve area. I think the dark lines on both sides of the burn area are a clue but i’m not sure what it means…any ideas?