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It is possible that font has corrupted. Open Font Book. Then select All Fonts on the left. Click on Edit menu and select 'Select All'. This will select all fonts. Then click on File menu and select Validate All Fonts. This will find all corrupted fonts. Then select all corrupted fonts and delete them.
Also in Font fine and select the Font. Then press delete or Command + delete keys on keyboard to delete that font.
Please let me know if that didn't work, so we can continue troubleshooting.
Also, Use this third party application named FontNuke to clear old font cache. Clearing font cache usually fixes 90% of font problems --> http://jamapi.com/pr/fn/
Let me know how it goes.