Summary:
Since you updated your Mac OS X operating system to Yosemite you notice that some of your musical notations or added text are not properly written or missing.
Steps:
You can easily fix this issue by downloading the Guitar Pro 6 Jazz font from this link.
Once you have downloaded your Jazz Font file, you simply need to add it to the Fonts folder of you Mac.
- Close Guitar Pro 6
- Open your Finder and select the "go" menu at the top of your window
- Select "go to folder"
- Enter the following address "System/Library/Fonts"
- Add the file you just downloaded to the "fonts" folder.
Your font issue is now fixed!