Mixed corn is a mixture of grains, of which some will be wheat.
As I understand it, wheat is best fed, on its own, whole, before bed, when the whole hard grains will help the bird process what's in its crop overnight.
If they eat wheat in the morning, it'll fill them up, and they won't forage (or eat pellets) as they should for optimum nutrition, not to mention getting some exercise.
With your hen not having her appetite back completely, I thought it would be a good idea to make sure she has some wheat to help her crop work. Also, they usually seem to love wheat above almost everything else.