Yep i see the problem. No worries that should be an easy fix. I thought when N pushed the level down. Bricks lower than the UI should be destroyed... obviously that didn't happen so will look into this one.
If you do find yourself for whatever reason in an unpassable level a work around is to pause the game and exit back to the main menu, the game will auto save your progress when you go to start a game again you can restore from the start of the level.