It is my understanding that chickens like higher roosts- are they huddling on the ground or do they perch on something in the run that is higher than they have in the coop?
When my chicks first transitioned to sleeping outside, they all wanted to roost on the remnants of an old playground that is in the run. Every night for a week or two I placed whoever was outside back in the coop and then shut them in for the night. Pretty soon, they got the idea and now they put themselves to bed every night!
I took the perch out of the roost that was there about a week ago. They are huddling on the ground. I have tried to put them back in the coop at night but as soon as I turn to get one another jumps out as my children laugh at me. I will have to try it when my hubby is home this weekend.
You can take them in and put them on the roosts for a few evenings, or give them the lock down and lock them in the coop for a few days. When my birds were little, I would give a little of their favorite treats in the coop in the eves. They got the idea and every evening they go in and on their roosts. Also I keep their feed and water in their coop.