M4a files "suddenly" stopped playing in Apple Music

Hello. I produce music, and often times, when I export a beat/instrumental from the program that it was created in, I convert it from a Wav. file to an M4a. file, using the default Apple encoder/converter. I have been doing this for years now, and have converted over 100 files to m4a. They have always played with no problems, up until a few days ago. Suddenly all of my previously converted m4a. files won't play in Apple Music. Ironically, they WILL play in Quicktime and in VLC, so they are not corrupted.

So, just this morning I thought to try and convert a recently exported beat (wav. file) to an m4a. to see if it would play, and lo and behold, it plays. So this tells me that Apple Music still plays m4a. files, just not all of my 100+ previously converted files.

Does anyone know if there was some time of update that made these previously converted m4a. files incompatible?

I have attached a screenshot of my current OS system

Thanks for any and all feedback. It is appreciated.