Dash lines in PDF not always showing

Hi,

I'm trying to export a project to PDF but I have trouble with the dashed lines. They all use the same line type, color etc but some of them apear as continuous lines when in PDF. I tried to set the scale of the line type all to 1 and not une the sheet scale but it still does the same. Also, If I do multiple PDFs without changing anything, some pages where the lines didn't apear dashed will be ok, and some that were good before won't be anymore. The dashed line also apear with way too big on some other pages. They all are the same line type.

Thanks for your help!