MP4 files showing old tags in mp3tag

Ok, I'm hoping this isn't a user error, because I've spent many hours trying to figure out what is going on. Also, it has me really worried because I don't know how long this issue has existed without me knowing about it - perhaps losing many hours worth of tagging work (I was frequently switching between Itunes and mp3tag for different tag operations).

It is best to offer a simple, specific example to illustrate the problem:

  1. Change title in itunes on a M4A non-protected file from "Test" to "Test1".
  2. In Itunes, right-click on the same song and "Go to file location in windows explorer"
  3. Looking at windows explorer details list: the title has changed to "Test1".
  4. Launch mp3tag on the file (from the explorer context menu). The title has not changed - it is still the OLD title of "Test".

I have no idea what is going on. Every other program into which I've loaded this m4a file (WMP, winamp), the title reads correctly "Test1". Only Mp3tag shows the old title. I've tried reverting to older versions of mp3tag, and still experience the same behavior.

Another piece of info: if I change the old title in mp3tag to "Test2", it reflects correctly in itunes as "Test2" (if I double-click the song). So, it's a one way issue - going from Itunes to mp3tag.

I thought this might have to do with tag priority reading (ID3 vs APE etc), but that doesn't seem to apply to Mp4/M4a files. Regardless, I tried enabling read of all three tag types, and no change. I also tried enabling each tag type individually - no change. It always shows the OLD title, and I can't find any trace of the new title (even in the extended tags window) - despite every other program displaying it.

Any help or clue would be appreciated, because I'm totally lost at this point.

BTW, I don't think I need to point out the danger of this issue, but I will anyway. Suppose you change a bunch of titles in Itunes (as I did), and then go out to mp3tag and mass-change a different field (not noticing the titles haven't been updated) - you just reverted all your titles back to their old values.

Just a little additional info:

  1. On the problem files, this problem is occurring with any field, not just the title.

  2. DBpoweramp reads the newly changed fields just fine. As I said before, the only application that shows old values is mp3tag.

  3. I have found that if I simply right-click on the file in windows explorer, and then go to properties, and to the details tab, and change the title, and then load the file into mp3tag, mp3tag will then show the newly changed title. And, more importantly, if I now go into Itunes, and change the title yet again, the new change is now reflected in mp3tag, and vice-versa from mp3tag to Itunes. So, just touching the file with Windows explorer editing (editing any field) appears to cause this problem to disappear.

I still don't know what's going on, but every piece of data helps I guess.