Hello there and welcome to BYC!
Do they have a specific place to lay their eggs? They could be eating them, especially if they are out in the open are bored. And once they get started on egg eating, there is no stopping them. I have a flock of egg eaters and the only way to stop them is to hang curtains over the nest boxes so that the box is nice and dark on the inside. They go into lay an egg and generally they leave them alone. I also keep fake eggs in there too, to stop the playing with eggs.
If they honestly are not laying eggs, they either have some health issue preventing them from laying or they are old hens that are out of eggs. Generally old hens act old, but it's hard to tell a young hen from an old hen other then her being slower than the younger ones.
Good luck with your birds and welcome to our roost!