As happens sometimes with Apple problems, there may be more than one solution to your problem. I found out how to resolve the greyed-out songs in my iTunes, so this approach *may* solve your problem. Thus I must add this warning. Please read it before proceeding.
WARNING: This solution worked for me. It may not work for you. Read carefully to determine if my solution will fix your problem. There may be more than one reason for a "greyed-out song." Applying my solution could fix your problem if we both have the same cause for this problem.
Keeping this warning in mind, I will proceed.
When checking my iTunes folders, I noticed that all the greyed-out songs in my iTunes UI had two copies in two different places.
iTunes>ITunes Media>Music>....
and
iTunes>iTunes Music>....
Evidently this was an irresolvable conflict for iTunes. My solution was to select all the music in the second location (iTunes>iTunes Music>....), copy all the folders into the first location (iTunes>ITunes Media>Music>....) then delete all the music in the second location.
Then I signed out of iTunes and signed back in, then activated iTunes Match again. The greyed-out songs were gone.
Again, this MAY not work for you for any number of reasons and I cannot promise that it will work for you. When it comes to fixing this, let the user beware.
Message was edited by: sphere777
Message was edited by: sphere777