I'm on top of Ubuntu 13.04, and when Firefox (and/or Chrome) renders a bootstrap icon, the result is the one I show on the screenshot.
I don't find any info about this issue, anyone has a clue about what's happening?
As i have this issue for a long time .. :)
The issue that in my Firefox settings (Content-> Advanced) .. I didn't check this option (Allow pages to use their own fonts,instead of my selection above) ..
So when rendering with my font .. I lost the icons ..
I hope that your issue is the same as mine .. to be solved with this solution .. :)