Chickens haven't laid eggs in 6 months

[Dominion]

I have about 20 adult chickens of various breeds and ages, all previously laying, that stopped in summer and have yet to start laying again. I've tried moving them around, restricting feed, overfeeding, feeding alfalfa as recommended by a neighbor, oyster shells, omega supplements, deworming with Wazine, still not a single egg. Not noticing anything strange in their manure.

Any thoughts or suggestions? I'm not inexperienced with chickens but I'm sure I'm missing something here. Thanks.

 

[HappyDuckie]

Are they free range? They may be hiding their eggs. How old are they?

 

[Sycamore Hill Chicks]

How old are they?

 

[Dominion]

Are they free range? They may be hiding their eggs. How old are they?

Between 2-4 years old

They are rotationally moved around pasture anywhere from 2 weeks to 2 months

Not hiding eggs, I'm hungry for them I'll find them

 

[Dominion]

How old are they?

Mostly 2 years old, a few are older