Hi
There is a problem with the Clip Jam and m4a files created by FFmpeg (or converter programs that use FFmpeg).
The FFmpeg people are working on a patch (for the FFmpeg program, not for the Clip Jam) . 
If people have m4a files that won’t play on their Clip Jam (because they might have been converted using FFmpeg) they can probably be fixed without converting them again.
The process is known as “Re-multiplexing”.
It’s a lossless process, the sound quality of the fixed files is just as good as the originals.
I used this method here —> https://www.hydrogenaud.io/forums/index.php?showtopic=109931
(Post #6 and Post #7)
There are other ways to do the job.
Google search for terms such as " mp4 muxer".
