Hi there,
This is happening because the site is calling the FontAwesome file from a different URL, and Firefox blocks these kinds of requests.
Here’s the exact error: Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://tron.uprm.edu/english/wp-content/themes/generatepress/fonts/fontawesome-webfont.ttf?v=4.3.0. (Reason: CORS header 'Access-Control-Allow-Origin' missing).
There’s a solution another user posted here: http://generatepress.com/forums/topic/since-update-to-1-2-1-no-mini-icons/#post-39797
Let me know if you have any questions 🙂