The font file might be in a place on the system that is hidden to Design & Print. On your Mac look in the Library > Fonts file, which can be in your User, Local, Network or System file, depending on where the access is. Here’s the Apple description of that….
If the font is there and still doesn't appear, it might be an OTF (open type font), which isn't supported. Only TTF (true type fonts) are supported.