I have a number of MP3 files for which the tags aren't showing up correctly in MP3tag. It may say the tags are invalid, or may simply not display them. For example, the title or artist may be missing when I view the files with MP3tag.
Yet if I look at those same files using iTunes or Windows Media Player the information is present.
I don't know enough about the structure of MP3 files to know if this may indicate a bug in Mp3tag, or whether the information may be in other tags that iTunes and WMP support, or what might be going on.
You should be able to find one of the files on Dropbox, via this link:
For that one, Mp3tag 2.57 says the ID3V2 tags are invalid, yet iTunes and WMP show all the information as far as I can see.
Thanks for any help you can provide.