Fancybox (WP Easy Fancybox) PDF links not working after re-sort of catalo

I have added a link field into my catalogue containing the URL of a PDF file for the itemlink.

The PDF file is then opened via Easy Fancybox which dynamically adds a fancybox-pdf class to the itemlink. Works fine until I select a sub category, which brings up a new set of results based on my selection. The link still works (opens in same window), but no longer has the fancybox-pdf class attached to the itemlink.

I tried adding fancybox-pdf class manually to the item link in Shortcodes.php. This appears in the HREF but still doesn’t call the Fancybox window).

Something seems to happen when I either search the catalogue, or narrow my criteria via the categories / sub categories. It seems to ‘lose’ the Fancybox call.

Any idea why?

I am currently running UPC Plugin version 2.5.3 due to another unresolved issue I just posted, but this PDF Fancybox issue is there across all versions I have tried.

https://www.ads-software.com/plugins/ultimate-product-catalogue/