Tag info shows up in iTunes but not in Mp3tag?

I use iTunes/TuneUp to fill in missing tag info, then i use mp3tag to rename the file based on the tag info. I have many files that show all the tag info in itunes, but when i load the same folder in mp3tag, the tag info is blank. If i look at windows properties for the file, the tag info is there. Why is the tag info not showing up in mp3tag? Any help is appreciated.
P.S. I have about 90,000 tracks that i am cleaning up and am about 1/3 complete. This is really helping me get rid of duplicates by renaming all the files using mp3tags, but cannot continue until i figure this out.

Those tracks may only have ID3v1 tags and you may have Mp3tag set to only read ID3v2 tags, or something like that? Check in the Tools-Options menu for your tag settings.

Have you tried looking at the "Extended Tags" for these files? (Right-click an entry in MP3Tag and select "Extended Tags...")



Yes, I found that if I convert all to ID3v2.3 using itunes, then remove all except ID3v2.3 usning Mp3tag that things seem to be correct now. Couple of extra steps but will ensure my entire collection is clean and consistent.