they need calcium, Flock Raiser is for youngsters.
Your laying hens have to have oyster shell to make the shells for the eggs.
Because Flock raiser is for all ages up to laying age, it doesn't have much calcium in it. Definately not enough for laying hens. They need oyster shell free choice.
Trust me on this, I have chickens, chicks and Ducks of all ages. I don't use Flock Raiser but my Ducks and growers are on grower feed, not much Calcium in it, either.
I put a bowl free choice of oyster shell and dried up crunched up egg shells and the hens and Ducks that are laying take what they need.
Even if you had them on Layer food, they would still need oyster shell or crushed egg shell available. They need more calcium than what they put in the feed.
If they don't need it they will not eat it. The young ones won't go near it until they are close to point of lay. That's how I tell they are close to laying. I watch that bowl and who is going there. Roosters and Drakes will nibble from time to time, those thick legs of theirs need a little more calcium, too.
Get them a small bag of oyster shell, about 3-5 days later you should have some eggs again. I go thru a 50# bag of oyster shell a year with 18-24 Hens. Now I'm cutting back it should last me a few years.
I mix the oyster shell and the crushed egg shell cause, they can use the crushed egg shell faster than the oyster shell, but they need new reserves, too.