I had a problem with Willie Nelson For the Girls FLAC download: the artist is always "Willie Nelson featuring ...."
I removed it from the library, corrected the tags so that Willie Nelson is the Album Artist and Artist, then ran an import - nothing added.
I tried importing the explicit directory - nothing added.
I did a global search in the files view - nothing found.
I did Open Media File and all the files are there and they are all playable directly.
I have never encountered this problem before and have been a user of MC for about five years, with a library of 80,000 tracks. Which is to say that I am not and expert nor a beginner, but generally capable around MC 20.
The only thing left to do, that I can think of, is to create a new master library and blow away the old. I would appreciate your advice.