Festival's playlists are not necessarily tied to a Collection.

For example, after a Collection reset, the songs in a playlist may not exist anymore.

The way Festival handles this is to continue holding onto the "invalid" playlist indefinitely.

Upon every Collection reset, Festival will check every "invalid" playlist entry and attempt to "recover" it.

If a matching song with the correct metadata is found after a Collection reset, any "invalid" playlist entry that was referencing it will automatically recover.