After a few more reports, I have more info about this problem.
If you have invalid formatting in the Notes field of a song or a show, the app will crash when viewing the Songs or Shows list. Unfortunately, you will not be able to see which song or show is causing the problem. But if you can open the Shows list, you should be able to open a show and view all the songs but the problem songs.
If you have invalid formatting in the Lyrics or Chords field of a song, the app will crash when viewing or editing that song. If you use the database sync feature, and you send a message from Help > Request Tech Support button in the app, and tell me the names of the problem songs, I can remove the formatting from them. However, I'm traveling today through Monday and will have limited online access.
If you can't wait for my help, another option is to edit the problem songs from a device that has not yet been updated to app version 4.0.8, copy and paste the lyrics and chords to a plain text document to remove all the formatting, then copy and paste them back into the app. Then sync your devices and the songs should display on all your devices.
This will be fixed in the next update, which I have already submitted to Apple, but Apple it's impossible to know when they will release it. At that point, you can use the Settings > Database Sync > Rollback button to restore the formatting you removed.
If you do not need a fix this weekend, please wait until Tuesday to contact me, since I will have limited time to respond while traveling.