Bearded dragon eggs w/o shells, and a question on an ex-stud.

Are you sure it is an "egg"? 1 egg is weird in and of itself, most clutches are 10 at the minimum. Could be very wet urates, especially if the animal was being poorly, high moisture greens with little nutritious value(iceberg, romaine, leaf lettuce, etc...). Eggs are laid very soft, and will harden. But that doesn't really sound like that. If she is hypocalcemic, she may have not had enough calcium to produce a proper shell. Do you have a picture of this? I'll ask around and see if anyone I know has seen anything like that. If it is an egg, there almost has to be more. If nothing else comes of this, you may want to check to see if she is eggbound. (Ultrasound is the easiest way, hopefully you have access to that at the school.)

If the males enclosure is good, (temps, basking, UVB, etc...) he just needs to be handled a bit more probably. He may have not seen greens and veggies much before, so you may have to tempt him, try some bugs on the greens, and try out different greens and veggies. "Curly" greens seem to entice them more, Mustard greens and endive especially, (not Belgian endive, you want curly endive, or frisée.) And any orange or red veggies, like butternut or carrot. Look over that list I linked to you before, and try different veggies until you find some things he likes.