Can the needed font be embedded in said file format? Or some other file format supported by the application. The application and post script fonts originated on Windows or in a Windows application and your issue has to do with Mac OS and Windows having different lists of fonts natively. You may not be considering it because it is failing to find a font. I'm also wondering what application is involved and whether the version it is on is the latest for the operating system. Start the unit in Safe Mode to clear the font caches (there are certainly other methods for doing the same but let's stick to the Apple-prescribed method for now):

Have you cleared font caches yet ? That should be step one. If the same font is loading in other apps as you've stated, and it's a system font (don't move it from it's location), then why are you assuming the font is the problem ? PS: System fonts are not located in /Library/Fonts It can be helpful to be explicit when seeking help, and/but you're starting with quite a few assumptions while deciding to leave details out, we still don't know what the problem application is. I asked you to specify because it's not uncommon for people to say that 'the latest Mac OS' in reference to an earlier version. The font came installed on the system, which is about a year old. The system and user library font folders. And if not, it needs to be eliminated as a factor before pursuing app specific possibilities. Once that it is resolved, it will likely resolve the app issue. The root of the app issue appears to be the Font Book issue. The issue I am here seeking assistance with is the Font Book issue described in the OP.

No fonts found in font book mac os