My mom used to feed them washed and crushed egg shells as a calcium supplement. Is that safe considering they may get a taste?That can happen the first several weeks when they are starting up. One of my leghorns kept ejecting shell-less eggs, then sometimes thin shelled eggs. Sometimes three total in a day. It was very messy and frustrating. She also laid her eggs from the roost, so even the good shelled ones broke when they hit.
She did eventually normalize, and now lays a nice white egg every day in the nest box.
Just keep offering oyster shell and she will be fine.