No thumbnails on the galleries

Hi, I’m running the latest version of this plug-in (pro 3.121) but just noticed that it has stopped working across my site (bereainternacional.com); you can see an example at http://bereainternacional.com/?p=8615 in the album at the bottom of the page). All of the photos appear as broken image links, but when you click on, the pictures are shown in full size.

Can you please help? I’ve resynced, checked the Fb album URLs, etc.,
Thank you in advance.

https://wordpress.org/plugins/srizon-facebook-album/