Why are my chickens staying in the coop all day?

Are they in the nesting boxes? If so, they’ve gone broody. You need to look up how to stop this as soon as possible. The short story is that you need to cool the hen’s underside.

We’ve used separation in the past, but I know people who have had luck doing a couple of bottom soaks in cool water. If you don’t, the hen’s health can suffer – including malnutrition, mites, and infections (from lack of dust bathing).

It likely is the stress. If they have food, water, space and light they should snap out of it.

Fear, age, weather or injury are the main reasons if it’s not stress.

Heat?

They have food, water, and company. Why should they leave?

I agree that they are probably stressed and just chilling for a while. Wait a few days before worrying too much.

Can you just put their food and water outside and make them leave the coop? Maybe I don’t quite get the setup. I would probably just pick them up and put them outside, and block the door, if they refused even for food and water,

Why can’t they just stay in their coop?

@KNOWITALL that’s what we give them. I forgot to put in the details that they stay on the roost unless the need food or water.