I'm using the mesh tool to create translucent highlights/shadows in Illustrator, but when I save as a PDF, the mesh lines become visible (see buttons below) and I can't figure out how to get rid of them. Any help would be greatly appreciated!
This kind of problem is common in PDF export, especially when using features that are bespoke to a particular piece of software, such as gradient meshes in Illustrator.
You may find that you can eliminate or minimise the problem by experimenting with your PDF export settings, but the only guaranteed route is to rasterise the offending elements before exporting to PDF. This may require keeping a backup copy of your design to retain the edibility, depending on your workflow.