I've installed Hummingbird, but it breaks the icon font in the social share plugin (just squares there). By turn, I tried to reset minification or other parts of Hummingbird. When I open the site in a new browser it then shows the font, but when I open the site again, they're gone again.
I used Enfold as a theme and Access press social share for the plugin.
If it does not help, please work on Hummingbird's minification setting, try to disable minification for plugins and themes one by one and evaluate its results, if it also does not help, go with file by file and identify culprit.
Hummingbird was deactivated, so that's why the icon fonts loaded without problems. I now reactivated Hummingbird. No problem yet. Then started with activating Hummingbird's caching: icon fonts disappear. Disabled caching in Hummingbird: problems remain, in both Chrome and Firefox.
I had a look at your setup and it seems like font file doesn't like being combined with other files, this actually happens quite often, so I disabled minification and combine for font file and it should be working fine now.
Please check by doing hard refresh in your browser (CMD+SHIFT+R on Mac or CTRL+F5 on Win) and let us know if it's loading properly for you as well.