You might try the granite grit? Not sure if that'll help but since they don't like the oyster shells it might be worth a try on that. All hens are different but mine love cooked oatmeal with a "hen safe" fruit added. They just go nuts, plus the benefit of cooking the oatmeal is it somehow has extra nutrients which could help your girl. Actually read a study about that recently, lol it must be the only food to gain nutrients when cooked!
Hens go broody when you don’t want them to… and won’t go broody when you do. 