Games not showing up when put in a folder you have added to a playlist

If you put games in folder you have added to a playlist, those games don’t seem to show. In which case, what is the best way to add a lot of games to a playlist you have already made? Readding the folder to a playlist duplicates games within the playlist.

You can either delete the playlist and re-scan or I believe there’s a “cleanup” routine from the playlist menu that you can use to remove dupes.