I don't quite understand your screenshot according to your text.
The screenshot shows us a lot of m4b files with tracknumbers that have no leading zero and 1 file that has a leading zero. The filenames just look the other way.
So could it be that you are want to change the filename to leading zeros and not the tracknumber?
Anyway:
https://community.mp3tag.de/t/not-possible-to-save-track-numbers-with-leading-zero-in-m4a/49664