I recently had a project that involved converting M4A files (which I’ve never had reason to work with before) to MP3 format, and I found a number of errors in the way Audacity handles tag conversion. When I import an M4A and then export to MP3, I find that the Edit Metadata box always has the Artist Name and Year fields as blank, and that the Album Title field contains the artist name instead. Yes, I realize that Audacity isn’t intended as a tag editor, but if it’s going to attempt to convert tags, it ought to at least get the basic info in the right fields.
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In this case, as you can see in the 2.1.1 Release Notes and in the table at http://wiki.audacityteam.org/wiki/FFmpeg_integration#Functionality the missing Artist and Year are a problem in the FFmpeg library that Audacity uses for MPEG-4 files. So the problem will be fixed when it’s fixed in FFmpeg.
Gale
I didn’t realize there was a separate Web page about FFmpeg integration. I did view the release notes when upgrading to 2.1.1, but missed the one line in there about this. 
Sorry for posting about problems that people are already aware of.
No problem - at least you looked. I’ve moved this issue into the “Imports and Exports (FFmpeg)” section for the 2.1.2 Release Notes to come so it should be a bit easier to spot.
Gale