They can lay a thin shelled egg that gets trampled or breaks on contact with a harder surface....and a broken egg is fair game for them to eat, leaving a mangled mess. Always good to take a pic of strange eggs when you find them.
Probably going to take some time for everyone to get settled in...
Could just be change stress.
How old is she? Could be change stress coupled with new layer syndrome, it can take up to a month or so for them to get it all in the groove and start laying regularly.
What exactly are you feeding?