When I try to auto-number several folders, with several songs each. I start renaming each song starting the filename by a number, and following by autor and name of the song. For the first folder the filenames would be:
/folder 1
'101 - autor - filename 1'
'102 - autor - filename 2'
...
/folder 2
'201 - autor - filename f1'
'202 - autor - filename f2'
...
and so on with following folders and files
after that, if I auto-number the files, for folder 1, starting with track number 101, folder 2 with track number 201, and so one, it seems that the auto-numbering does not work properly for track numbers starting with 301 and greater.
I didn't care about ID3v1/ID3v2. The problem is that I was
unable to assign a track number equal or greater than 301.
With your suggestion I have been checking for the type of tag and now is clear for me:
As you suggest ,the problems appears when I use ID3v1 (or the file comes with a default ID3v1). I have checked with ID3v2 tags in files and the autonumbering works perfectly.