HI!
I have had this problem too. I'm sorry, it can be frustrating. The first time it happened, I wasn't able to tell which chicken was doing it. So I just covered all of my bases. I deep cleaned the coop and made sure it was secure, added a pecking block (the solid block of compacted scratch and feed) for stimulation, made sure the food and water never got low at all and fortified the food with added herbs and egg shell (for quicker calcium), put oyster shell (for even extra slower calcium) in a separate dish so it could be accessed, and also made sure to grab those eggs multiple times a day so they didn't sit too long. After a couple of days it happened less and after 2 weeks I stopped finding pecked eggs.
The second time it happened, it was my fault. I have a chicken who likes to kick the bedding out and they were cracking when they were laid on the bare wood, adding more bedding solved the problem. The third time it happened, on of my girls was just old, I had to isolate her because nothing worked and she wouldn't stop.
I hope something in all of that helped.