Syncing music from CD on my MacBook and then my iPhone

Hi! I know its not a new issue, but I've just recently run into it and have not yet found a solution. I have recently started a physical music collection, and have been importing the songs onto my laptop, and then synced them with my phone. Everything was fine, till about a week ago, when the album I sinked became unavailable. They are shown on my phone, but when I try to play them, I get a popup saying "This object is currently not available in your country or region" (translated from German).

I've tried deleting them, and syncing again, but that didn't change anything. How can I sync my music again? I think it's a bit weird that my phone can just make them unavailable for me, even though I literally HAVE the music.