We have already noted this phenomenon.
/t/11709/1
The problem seems not related to Mp3tag but to other software on the target system.
Numbers resp. number strings (!), which contain only digits from 0 to 7 and begin with 0, are interpreted as octal numbers by the other software.
Do deeper search into this direction.
The ID3 standard for ID3v2.3 and ID3v2.4 says:
TRCK
The 'Track number/Position in set' frame is a numeric string
containing the order number of the audio-file on its original
recording. This MAY be extended with a "/" character and a numeric
string containing the total number of tracks/elements on the original
recording. E.g. "4/9".
So the Mp3tag tag-field TRACK (ID3 TRCK) contains a 'numeric string', not an octal number.
You can verify this with a hex editor for yourself.
Bewildering ... do you mean leading blanks or leading zeros?
Are you aware of the Mp3tag scripting functions?
The $num(,) may be of help to format a number as needed.
DD.20120120.0552.CET