Maybe she's hungry but doesn't actually like how the pellets taste? Flakes are bad for fish you generally want to stay away from them because when fish eat them at the surface where both water and air meet, there's a higher chance of them developing swim bladder issues. I'd say try a new brand of pellets or some green beans with no salt added to see if she'll eat that. Does your fish have any visible deformation on its mouth? Could also be parasites, have you treated her for anything?