I have a fleet that I don't want to move for a while, so I've been hitting the space bar to pass its turn. Now another ship, on autopilot heading to a distant point, has ended its turn in the same tile, so it's stacked with the fleet I don't want to move. While cycling through my idle ships the fleet in the stack is selected, and the space bar doesn't work. There doesn't seem any way to pass on that fleet unless I move it.
