Do you have a light in the coop? Try using a timer that leaves it on for an hour or two after sunset and delay the door closing till a little later, if yours is adjustable. The light tends to draw them in. This has worked for me.
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I checked the door yesterday and it closes about 8:50. The past two nights they were still outside. I went out at 8:45 and herded them in the pop door to show them that they are supposed to go in that way, and not be carried in through the human door. They had no visits other than food and water refills. Now they're being annoying.I don't know where in NJ you are, but sunset in Newark when you started this thread was 8:13 PM (anything further west would be later), so 8:30 was only 17 minutes after sunset.
When my chickens are out they sometimes don't go in until 20-30 minutes after "official" sunset time. I live on the east side of a ridge so the sun "sets" here about 10 minutes earlier than that, so they're not going in until 30-40 minutes after the sun has "set".
Really, unless you think predators will get into the run sometime between sunset and dark, try leaving the door open longer. And don't let them see you checking up on them because they'll probably stay out expecting treats or other attention.