We have built a custom icon set using Illustrator to draw the icons, copy/paste the shape to Glyphs, export to ttf, use font squirrel to create the various versions of the font.
All the icon work on all browsers except IE. In explorer 9 and down the "t" which is the twitter logo does not render.
I have re-exported the font several times with no luck. Has anyone ever heard of this. Could the vector drawing be wrong somehow?
When pasting a shape from Illustrator into Glyphs you must "group" the shape in Illustrator. Even if the shape is one path.