Music Disappearing (Roon/Tidal/Qobuz)

With to Amazon. I've never had a problem. 

I've seen this often with playlists.  In every instance, I was able to go back and find the missing album/song.  I suspect the original song may have been removed and replaced with another version, but the playlist is still looking for the old version.

You may see a lot of this on Tidal as they replace MQA albums with FLAC versions.

+1 @jimmy2615 ​​​​@dinosore. The same has happened to me in Roon. It took me awhile to think of searching through "versions" and the artist’s "discography" to find a new or the "moved" verision of the album. So far, worked every time, no "unavailable" albums in my library.

While not on Roon I occasionally have albums show up as no longer available… but in fact they are. I assume they replace them and some intermediate software detects temporary absence and marks them as gone… but they are there. 

It seems this is not uncommon, since what you all have described below is pretty much exactly what happened to me.  Thanks all.