Do a search on the forum for the word blank or document & you'll find some solutions or suggestions at least. They can be fixed. There was an iTunes utility (no longer made) which allowed you to drag & drop any mp3 onto it & it would change the file's icon & default app to open it to iTunes. You can have it if you want it. I spend too much time in osx nowadays.

I forgot to mention, they other way is (in the short term) to drag & drop those files onto iTunes. That works!