hidden characters in tags

Having trouble with some of my mp3s getting extra characters in the tags.
These characters don't show up in Mp3tag, but other programs have problems with them.
Basically, it is adding an extra character at the end of all populated tag fields.
Specifically, what is messing up other mp3 programs is the illegal character added to the track number.
Attached is a screen capture of what shows up in Mp3/Tag Studio, for example.
Here is my tag string:

%artist% - $num(%track%,2) - %title%


Problems with ID3v2 tags in Unicode format?