I have been a long-time user of mp3tag, even though the problem mentioned in the subject line has actually existed for many years and is annoying.
The problem is that virtually all common systems and apps on the market, whether they are apps on the PC that read MP3 tags (foobar, MixedInKeys, Windows Media Player, Virtual DJ, and a lot of other MP3 tools and players), apps on smartphones, TVs, or even in cars, can read virtually all tags created by other apps—only mp3tag seems to do its own thing. For example, if I tag something in MixedInKeys, practically no tags appear in mp3tag, especially not basic ones like artist or title. Let's not even get started on integrated covers or special tags like Key, even though I defined them correctly in mp3tag (it worked for a short time, then suddenly stopped). I know how to create the KEY tag correctly; I've managed to do it in foobar. If I download an MP3 from somewhere (without knowing how and with which app the tag was created), it is still recognized by practically all apps, but very often not by mp3tag.
This means that if I want to use mp3tag, I have to laboriously recreate all the tags for almost every MP3 file, even though they are already contained in the file. I also have to search for and insert the cover image again, even though it was already contained in the MP3 file.
Now the question for me is why practically all apps can read the tags correctly from all other apps, but mp3tag can't? Of course, all other apps can read tags created with mp3tag, so why doesn't it work the other way around?
The tag options in mp3tag are for reading ID3v1, ID3v2, and APE, and for writing ID3v1, ID3v2, APEv2, and ID3v2.3 UTF-16. Does anyone know how to solve this problem? I would actually like to stick with mp3tag, but it's gradually becoming too annoying for me.