Apple Music Songs won't add to library on multiple devices

I have looked for a solution to this problem, and nothing has seemed to work.

I know variations of this problem have been shared, but not my exact problem.

I will preface this by saying my membership is active and up to date and sync library is turned on.

Problem:

I search for an artist on Apple Music, find what I am looking for, select and album and click/tap the "+ ADD" button.

The button disappears for a moment, so I know I have selected it. (When I do this on my Macbook Air, it acts as if it is in the process of adding).

A moment later, the "+ ADD" button re-appears, and the music/album/ song has not successfully been added to my music library. I try again, with the same results.

I have tried this on my Macbook Air, work PC, Phone, internet browser, Apple TV... all with the same result. The "+ ADD" button almost returns immediately.

I have tried shutting down and restarting, logging out, disconnecting from wifi (on phone) and adding via cellular network, etc. all with the same results.

I have tried multiple songs/albums/artists, again... all with the same results.

I know it was working today, because I had added a handful of songs/albums successfully. I know this, because those albums show up in my "Recently Added" tab.

Any suggestions?