I'm having issues when exporting a layout to PDF and then when printing, lines between the vector data of only one layer seem to be appearing for some reason. I've included some screenshots below.


The image on the left is the PDF opened in Adobe and seems to be all good. The image on the right is the printed copy.
Does anyone have any ideas as to why this is happening and some workarounds? I'm printing a lot of map series and converting to image makes the files way too big so trying to find another way of keeping the size down without having this issue.
Any help would be greatly appreciated!
Cheers,
Kurt