Consider to open the file in a vector program such as Illustrator or Inkscape (free). Set the stroke to a normal figure and the fill to nothing. This should result in the interior lines being visible.
If you don’t have either program or care to not make the installation, post the LB file or the SVG (if allowed) and I’ll take a look at it.
You can do as Fred suggests. You can also save an image of the ‘Preview’ window if that helps. I do want to check something, do your cuts process correctly when running this job on the laser?
The problem is that LightBurn exports all the shapes as independent, instead of merging them into a single filled path. It’s on our list to fix, but if you open the SVG in InkScape and choose ‘Combine’ (I think) to combine the multiple paths into one, it works.
I had to do a combine, then break apart then difference to get it to work. It used to take me forever to do mockups before you mentioned how to fix this in Inkscape. Another thing that would make mockups easier for me is to export preview images as transparent png (or have that as an option in export).