While it is true that hens have sat and hatched in all sorts of nests in all sorts of places when confronted with difficulties, optimising the nest may give better results.
Ideally the hen needs to be able to easily control the orientation of the eggs and her position on them.
From the pictures it looks as if the hens feet will be on the coop floor which is plasic and slippery. From the pictures again, it looks as if the nesting material is very shallow and the eggs may be in contact with the plasic floor.
I see her coop is open to the outside which is great but imo the nest itself is far from optimal.
What your hens nest doesn't have is a hollow in the nest. This can be very important as it helps the hen when turning the eggs to keep the eggs in a tight pack. This allows better control of temperature and humidity and position.
This article may help explain a bit about the problems a hen may have in controling her eggs.
https://www.backyardchickens.com/ar...e-make-a-sitting-hens-job-so-difficult.74389/
Assuming the eggs she has sat on have all been fertile, to not hatch a single egg seems to me to be unusual given she's a dilligent sitter. Have a read of the article and come back to this thread should you have further questions.
Regarding weight loss. It is very difficult to judge weight gain or loss when a chicken may weigh 7 or 8 pounds. A few ounces when dealing with these kinds of weights is a lot. Should you decide to let her continue sitting on a new batch of eggs then weighing her will give you a much better idea of the physical toll.