Purchased iTunes songs available only in preview and not playing in Purchased Playlist in Music Library

I purchased several albums, on different dates throughout the years from iTunes. All these songs were stored inside the Purchased Playlists across all my devices (iPhone (s), iPad(s), macbook pro).

Recently, I noticed they are not available to play, though they DO show up in the Purchased Playlist, but in preview (the few seconds preview you normally get on iTunes, before you purchase the song, as if I never purchased them).

Dates of purchase range from 2 years ago to a couple of months ago, and those that wont play are chosen, I believe, randomly.

Or maybe not that randomly! Because the strangest thing about this, apart from feeling ripped off, is that not all songs have this, but those that are "most popular" (as per iTunes ratings). So out of an entire purchased album, I would have the least popular songs available to play, and only previews of those that are popular. Regardless to say, these songs have been removed from al custom playlists and I cannot add them to any playlists, as I am getting this message:

I have refused to rent these songs and subscribe to Apple Music, therefore, I PURCHASED them out of respect and support for the artists. Now, when I want to listed to them, I get a message saying I need to re-subscribe to Apple Music (I NEVER SUBSCRIBED!!!!!). I don't want to subscribe, I just want my purchased items to be available to PLAY.

One more thing: I am using the same device I used when I purchased these songs, so a cross-device synch issue is out of question, for sure.

How can I restore these back into my device/s? Why are these songs appearing in my Purchased Playlist in preview mode and how can they be restored?

Thanks a lot!