I think the problem is that the coop is elevated. I have the same problem with my elevated grow-out coop but don’t have that problem with my coops on the ground.
I just wait until they put themselves to bed and it’s dark so I can catch them easily and lock them in the coop. Sometimes it only takes a few times, sometimes it takes three weeks before all of them catch on. Unless you make another gate or door in your run, you don’t have access to do that.
If you consider your run predator proof, you can leave them alone. Once they start to roost at night they should start going to bed on the roosts. My brooder-raised chicks typically start to roost somewhere around 10 to 12 weeks of age. I have had some start at 5 weeks, some take longer, but 10 to 12 weeks is fairly normal.
Another possible option is to train them to come when called. Use the same container and put a treat they really like that rattles in that container. Use a call like “Here, chick, chick” or whatever you feel like when you give them that treat. Once they come to the call and rattle of the container, trick them into going into the coop near bedtime and lock the little boogers in there for the night. Show them who can outsmart whom! Eventually they should get the message and start putting themselves to bed.
Good luck and welcome to the forum. This can be frustrating.
