Like your avatar! Those yolk less eggs are called wind eggs I think. I get those sometimes too, from my young hens. Like a little popped balloon. Maybe these anomalies are just part of the normal egg laying range?
If she's generally in good condition then maybe a boost to the diet with BOSS and eggshells might be enough. As for leaving the nest box, that's another puzzle isn't it? Is the other hen overly protective of it? Is it maybe not private and quiet enough there? That's not a nutrition question...
Hmmm. I asked her age because my older hens had very brittle eggs. But they were four, five years old. Some experts will I'm sure weigh in, but maybe she needs more protein than the layer pellets? Offer tuna fish, scrambled eggs? I learned about black oiled sunflower seeds from this site and my...