I have known for this issue to occur for a while now, while I've only just realized to report it for a future fix for the software.
This issue occurs...
All Operating Systems from Win 7, 8 & 10 (64bit)
Versions of mp3tag (tested from probably 2.70 onward)
Tested using .M4A file format
When using the auto-numbering wizard beginning at tracknumber: 1
and only selecting the "save total count of tracks" radio box
by processing a compilation full of tracks at once (say 20 or more) quite often, verified by showing up in iTunes, will sometimes skip the total count of the track number when being processed.
I have 20 tracks to use the autonumber wizard on.
I select all 20 tracks
Check the "save total count of tracks" radio box
mp3tag then processes the 20 tracks
once completed, after dragging the tracks into iTunes, and looking at the 'TRACK #' column in the songs view, it will quite often show 2 or sometimes more missing the "of 20" part, and will only show "1" or "6" etc. not "1 of 20" or "6 of 20".
Seems to perhaps be a glitch or bug, as it's inconsistent and happens at different timings frequently. Perhaps the software is processing the tracks too fast, and will sometimes skip over one if the file can't be read fast enough (I am using an SSD however) there's no error messages that ever show. Perhaps slow the processing of this wizard down may help?
Would love to hear a response back on this one...
Within Mp3tag a 'blank tag-field' does not exist. Do verify whether your track writing procedure has created the tag-fields TRACK and TOTALTRACKS within the m4a file.
If there is one m4a file, which does not contain the tag-field TOTALTRACKS, then try to find out how.
See also ... /t/2889/1