problems with icon fonts and ultimate branding plugin

Here's my setup... In the CSS tab of Ultimate branding I have added a font-face tag linking to an icon font set within my main domain. I have also added all of the font's CSS as well (i.e. .pe-7s-graph2:before {content: "\e64c";}).

I am then referencing these styles within the custom dashboard widget plugin.

Here's where things get weird...

The icons show up on some sites and not others. Even stranger, I can log in using two different browsers and can see the fonts within one and not the other. (For instance, SITE A works in Chrome, but not Firefox, while the main site works fine in Firefox as well, so I know it's not a browser issue.)

Hope this is clear as I am sure it's a fairly unique scenario.