Noticeable Change in Image (flattened line buildup) After Exporting

I recently exported a project and noticed that all of the line quality that had been built up while drawing in a layer (a vector layer at 10% opacity) had been flattened out to an even grey in the export. Is there a way to export the image so that it doesn’t lose that information?

To clarify, see attached image files for comparison. One is a screen grab of Storyboard Pro. The other is the same panel exported as a jpg.

Layering transparent vector strokes isn’t the best way to
get this effect. It looks to me as if you’re trying to use a
bitmap (raster) image workflow using vector tools. Try
drawing in a bitmap layer instead of using bitmap tools.

That said, I’m not sure why the lighter part of the image
seems to have a low-cutoff value for the grey lines
“underneath”. It could be a by-product of additionally
limiting the alpha value of the entire panel perhaps.
Did you maybe add a transparent layer of white over the
top (excluding the black strokes)? If so, try removing the
transparent white layer.