Dashicon, Font Awesome, misc icons become squares after activating

Hi, so first off I have to say I am still pretty new to all of this and still learning so my apologies if I don’t use a lot of the technical terms for things.

I was working on a page for my site today when i noticed that most of the icons in the admin bar (during a preview as well as live page) and icons in my menu had all been replaced with empty squares. I wanted to make sure that I checked and tested as much as I could on my own before posting here, one, to see if I could fix it myself and learn something new, and two, to be able to provide as much information as possible to anyone who can help. Following are the steps I tried in fixing this:

Checked to make sure that Dashicons and Font Awesome fonts were all enqueing properly and that their folders were located in the correct places on the server, and that all links to said folders were correct. Everything there checked out fine.

I then began inspecting and testing the code of the page to see if there were any error being reported that would relate to the issue…none were found.

Once I was sure the coding was fine, I checked the pages in all the browsers I had available, being Chrome, Edge and IE for Windows, and Safari and Chrome for Mac (all updated to latest versions with caches cleared) Issue persisted through all the browsers.

I also made sure that caching was disabled on my server

I then began disabling plugins to see if I could narrow down if there was a conflict, starting with optimizing and security plugins, then clearing all caches and re-loading the pages after each deactivation. No change, until I deactivated the UPG plugin, then all the icons came back.

To make sure, I then disabled the remaining plugins, to make sure everything looked ok and to have just the WordPress core running, and after clearing caches again, enabled UPG and tested and sure enough, the icons became the empty squares again.

At this point, I do not know what else to try, and I am open to any suggestions. Thanks.

The page I need help with: [log in to see the link]