Error -54 uploading mp3 files to Music.app

They're from an exfernal drive into my Mini M2 Pro 16G

Songs from the same drive link and play if the song is already *in* my Music.app, but new ones fail.

It's a very simple situation --- permissions on those files, that new folder, and on all the meta-folders and drive are all either you can read & write or you have custom access.

I'd appreciate any hint or help.