Ever since the update, none of the lyrics display when a song is playing anymore.
I've never heard of this app before but I just went to the market to check it out. Sounds cool... but anyways, to answer your question... Down in the comments of the app it says if you uninstall it and then re-install it will work again. Hopefully that helps.
Ideally the native music player in Google would display embedded in lyrics like the iOS and Windows Phone players. If you want this feature too, let Google know by staring the feature request below.
Issue 32547 - android - Add ID3v2 Lyrics Support to Media Database - Android - An Open Handset Alliance Project - Google Project Hosting