Playlist folder problem

Hello!

In my iTunes library, I have a special folder for playlists that I automatically sync to my iPod, to separate them from my regular computer playlists.

However, starting this past week, some of songs that I have removed from the iPod playlists, still show the folder when I right click on them. I wonder why an empty folder is visible even though they've been removed?

It's a bit difficult to explain (English isn't my native language), so I've included a screen shot:

Also, starting about a week ago, some songs no longer show the folders at all, just the playlists. Have I done something wrong?

This is the correct listing, which most of the songs still use, showing the folders:

And this is the incorrect listing, without folders, that recently added songs show:

Thanks in advance for your help.