No the files just say “not available” on my computer, and I can’t do anything with them, although they are still listed.
To clarify, do you mean the files listed in iTunes or Finder (I think that's what it's called). If you mean iTunes, then it sounds like the songs are missing their location information or are indeed missing.
On the other hand, if you mean Finder, it's possible the files have lost their association. Again, I'm not very familiar with iOS. With PCs, music files are generally MP3s, movies MP4s, pictures JPGs, etc. If a music file looses its .mp3 association, the computer does not know what to with it. Re-associating the .mp3 designation allows the computer to play them as music again (provided it hasn't been corrupted). Is it possible something similar has happened?
Sorry I couldn't be more helpful, but hope some of this helps
An additional thought... Have you considered contacting Apple or searching through Apple forums? They might have more insight as to what actually happens with iTunes and media when backing up to the Cloud. The Apple forums would reach a more target specific audience who might be able to provide additional information.
Hope this helps
Nope none of the suggestions offered did anything at all. And some more songs have greyed out too. Like random ones in the middle of an album. Not playable. So weird. I’m hoping an update or something will fix it.