I've had it happen on both Apple Music and Spotify. Given my 40h+ master playlist, I tend to notice it. I always have a few gray holes. As for replacements, my

I've had it happen on both Apple Music and Spotify. Given my 40h+ master playlist, I tend to notice it. I always have a few gray holes. As for replacements, my understanding is that they are often due to the better royalties on original artist re-recordings. I always try to switch back to the originals, and AM, my current service, only sometimes still them. Frustrating to build a collection on shifting sand.