I have an mp3 with tags which display inconsistently between winamp and mp3tag. When I load the mp3 in WMP the same tags as shown in mp3tag are shown. I opened it up in a hex editor, and I found two sets of ID3v2.4 tags at the beginning of the file. It appears that mp3tag is editing the first set, and leaving the second. I don't know how the file became this way to start with. I suspect that there was originally a v2.4 tag, and since I had mp3tag use v2.3 it prepended the file with a v2.3 tag. I then later switched over to v2.4 in mp3tag, and the ID3 tags at the beginning became converted to 2.4. Winamp however seems to display the second set of ID3 tags instead of the first.
Can someone confirm this behavior?