Build brick-building sets from the perspective of a minifigure. · By DasMatze
Just like real LEGO, sometimes bricks fall through the floor and can't be retrieved. I have had 3 Levels that are unwinnable because of that.
That normally shouldn't happen and they are supposed to respawn once they move beneath the surface. I will look into it later but for now try exiting to the main menu and continuing the saved game. It should respawn.