How do I regenerate new playlists for a CD that was ripped to FLAC without having to rip the CD over again?

In R16.4 there was a bug in the Playlist Writer DSP that was passing track 1 filename for all tracks on the CD in BatchEnd. I ended up ripping my entire collection (800+ CD's) to FLAC before I noticed this bug. Subsequently all of my FLAC rips now have messed up playlists.

I have tried using Music Converter in Test Conversion mode and adding the Playlist Writer DSP and it does create the playlist, but all the tracks have a file extension of .IGNORE. Am I missing something obvious?