Plugin doesn't work since 3-4 days ago

Your plugin is not working on these urls http://www.mtxm2m.com/en/about-mtx-m2m/ (ENGLISH) and http://www.mtxm2m.com/sobre-mtx-m2m/ (SPANISH) and I don’t know why because if You open the link in other tab, it works perfectly. Can you check it? Thanks a lot!

https://wordpress.org/plugins/pdfjs-viewer-shortcode/