Juno, are you sure she's not moving?
I've had a broody who's been sitting just inside the garage door and I had assumed for the first week or so that she'd not been moving at all. However, over the last couple of weeks I've spotted her out and about a couple of times. But today, when her chicks hatched, she drank all the water in her bowl for the first time since she started sitting. So I can only conclude that she had actually been out every day for a drink until today when the chicks finally arrived.