Are you saying that this 'Ø' symbol is part of a Diameter dimension or just when a symbol inserted in a note? Could you provide a picture of the results that you're getting? What font are you using?
Font is Arial Unicode MS
These just look really tiny, especially in the threaded hole callout.
This is from another drawing:
Seems like they used to be closer in size to the test.
You indicate that you're running on Windows 8.1. Did you recently upgrade to Windows 8.1 or did you start with new system and install NX on it? I ask because it's possible that you may not have the additional NX TrueType font libraries installed. Go to the Windows 'font' folder and see if the following font files are found:
NX ANSI Symbols Italic
NX Constraints Regular
NX ISO Symbols Italic
If not, you may need to run repair on your NX 9.0 installation.
Sorry, I wasn't able to reproduce the problem with NX 9.0 on Windows 7. Note that this and many other symbols are not dependent on the font being used as long as it's one of the system installed TrueType or OpenType fonts. You might want to give GTAC a call as it's possible others have reported this problem and know how to address it.
We had the same problem on a few of our drawings when we changed over to ISO standards from ASME. Our new font is also Arial Unicode MS. We have a program to change all the annotation settings and rerunning this program cleared the problem. You may be able to update the drawing annotation settings manually to do the same.