How to stop WooCommerce from removing link functionality in uploaded PDF products

my site uses WooCommerce to sell downloadable PDFs which should have clickable links, but when these PDFs are downloaded after purchase, the links are no longer clickable. I’ve searched everywhere I can think to try to find a resolution to the problem. Has anyone encountered this before?

I’ve tried downloading with multiple browsers and opening the files in Acrobat and Preview, to no avail, so I think it looks like the links are being removed on upload to the site. I use an image optimiser (Smush) to process images on upload to the site, but this doesn’t affect PDFs.

I’m a little perplexed, any insight would be much appreciated.