Cannot import an MP3 to the Music app

After reviewing all of these recommendations, I am finding that I have the same problem, but it remains unresolved even after attempting the above. Just recently updated to BigSur 11.6...I don't know if the system update is causing further complications. Additionally, all of the original music was mapped over from the old iTunes files. I took all the original working mp3s out of the iTunes files, copied them, imported them to the newly updated library (using music/music pathway), and removed the iTunes file structure holding all the old information, just in case there was confusion between the different folders/retrieval/storage/etc.

I still have not been able to resolve the original problem, I cannot import and play new, functioning, mp3 files that I have on my Mac.

Fouren wrote:

Yes, it works with an mp3 that I copied & deleted from my library. This is really strange... What's the explanation? How can I add other files?

If the old ones still work in iTunes, but the new ones don't, I'd conclude that something has changed in the tools or procedure that you are using to create the MP3s.

I've created it the same way as the old ones in my library,

Fouren,

Find one of those old MP3s that works. Drag the file to your desktop and delete its iTunes library entry. The re-add it to your library. Does it work?