How to help her figure out nesting boxes?

2/3 of my chickens that are laying are using the nesting boxes just fine, but one of them just… refuses lol. She’s laying her eggs directly on capstone blocks, which in turn has led to them all cracking as she lays them. I used a couple ceramic eggs at first and the others picked up on the boxes no problem. I placed her in the box and she likes it in there, just won’t lay her eggs there. It’s kind of comical and I wouldn’t mind if the eggs weren’t cracked. Will she figure it out on her own eventually or does she need help? Or should I just suck it up and pad the blocks really well and let her lay her eggs where she pleases?