They can be vvveerrryyy sneaky!
Might be time for an exam:
https://www.backyardchickens.com/articles/who-is-laying-and-who-is-not-butt-check.73309/
Then maybe .....
Free range birds sometimes need to be 'trained'(or re-trained) to lay in the coop nests, especially new layers. Leaving them locked...