One of our Buffs did the same thing in the summer. She was obviously broody but wouldn't stay on the nest even though it looked to us like the space was fine, but we removed a divider kind of on a whim. The doubled nesting space apparently met with her approval because after she went in to lay her very next egg, she didn't want to get back up. There were many days over that following 4 weeks that we had to force her out of the coop to take a bath and eat.