At NC State, we use a font-icon set where letters are assigned to the content property in the :after psuedo selector. In one instance when I was trying to call a font-icon in an HTML element, I noticed the icon wasn’t rendering.
Looking at the console, my team and I discovered an issue with font-icon files being served from other subdomains. We were able to mitigate this by changing the CORS settings on our server.
After fixing the server issue, I still noticed that the font-icon wasn’t rendering.
One of the other devs pointed out that the content property of the icon I was trying to use was applied to a lowercase letter. Checking all the styles on the element, we noticed that it had a text-transform of uppercase. Which to my surprise also made the content for the pseudo selector, uppercase.
Applying a text-transform: lowercase to that element seemed to fix the problem.