Can't open .m4a or .wav files in my Apple Music

I like adding custom audio files I record to playlists in Apple Music. I have no problem creating AAC versions so they sync with my cloud library... but some files just won't show up in Apple Music (AM). I can double click the file in finder, or right click and ask it to open in AM and AM opens (if not already opened), and yet no file plays.

If I try to import using AM and select the file that way, still nothing happens. I never "see" the file in AM.

Any thoughts?

The .m4a audio was recorded using Quicktime player and the .wav file was creating using my rode procaster.

UPDATE :::

I just clicked on an .m4a file that will play and one that won't work. Here is the file info:

WILL PLAY :

audio channels : Mono

sample rate : 32 kHz

WON'T PLAY :

audio channels : 8

sample rate : 48 kHz

Could this be a reason??