I have found that there are some albums in my collection that simply refuse to accept cover art no matter what I do - copy and paste from scanned cover art, sources on the internet, etc. It has happened on approximately 50 out of 3000.
The playlist/smartlist/missing cover art helped find them but it was not entirely correct because it found tracks that did have cover art. It could not find any of the cover art on the Internet. I have been able to find the cover art on the Internet but I cannot paste it to these albums.
For example I have a boxed set of 80 Leonard Bernstein CD's that I have ripped to Media Center. Most of them accept the cover art but there are a few that will not.
It is completely inconsistent with random missing cover art on classical and popular, wav, flac, mp4 files etc. Sometimes the wav version will accept the cover art but the flac or mp4 version of the same album will not. This makes no sense.
I have gone from Media Center 18 - 24 with exactly the same issue.
Has anyone else had the problem and what might be the solution?