They don't see in the dark, and inside the coop is darker than outside. Once the light levels are too low, they don't know where to go. And cannot judge the jump to a roost in the dark.
Try placing a light in the coop and turn it on just before dusk and they should start going in on their own. Just a regular low wattage bulb will work, set it up so you can unplug or use a remote operated outdoor cord so you can turn it off easily once they enter and find a roost position. This worked for me when mine were moved from the brooder to their permanent home. It was quite a challenge to move them in every night, but the first night with the light they all marched up the ramp to roost. We used the light for a couple of weeks and after that they would enter at dusk without the light.
Once I had a pullet caught in the dark laying an egg very late. She came out and went out to the dark run and was really distressed. I shined a flashlight thru a window into the coop and she happily ran up the ramp, got on her roost and settled in with the flock.