Print PDFs not working (blank) in Firefox

Whether I click a print.js button on my site (on localhost) or on the Print.js Crabbly page, if it is for a PDF I get the correct number of pages but they are blank. Works as expected with images (from Print.js homepage) or in Chrome with PDFs on my site. If I open the PDF in Firefox directly and send to print it works, so this seems limited to Print.js and Firefox. It worked a few weeks ago and I can't think what setting I have changed within the browser since then that may have caused it to stop so wanted to check if others were having the issue.

I am running Firefox 110.0 (64-bit) on Windows 10 Home v22H2 - build 19045.2604