Tags for AAC audio

I have extracted audio from a Youtube mp4 so it’s AAC in an mp4 wrapper with no video. I then tagged it with mp3tag (which it will do only if I give it an aac extension).

The wiki says Kodi is supposed to read ‘mp4’ tags, but it won’t add this file to the library either with an aac extension or m4a extension. If I give it an mp4 extension, Kodi thinks it’s a video so it doesn’t show up in Music Files.

How can I add this file to the Music Library?