I'm having a similar issue but with a system font. One of my documents has Myriad Pro in the template layer, which has been working for the last 5 or more years across different versions. Whenever I open it in Illustrator CC 2014 it thinks the font is missing. It still works fine in CS6 & CS5.
Thanks for the reminder of clearing the font caches since it's something I've had to do many times before. I'll try clearing them when I get back to the office Monday.