Only thing I can think of is a game camera. Inside the nest area, and review footage.
The other possibility, is the eggs are getting broken when the hens step around.
At that point, most chickens will wolf down cracked eggs.
Egg eating is a difficult habit to break. Hopefully yours are just opportunists eating accidentally broken eggs.
Are the shell strong on your eggs??? Weak shell will break easily, and the usual cause is calcium deficiency.
What are you feeding your hens, and do you provide additional calcium free-choice???
WISHING YOU BEST,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, and