It sounds like you're being very thorough and doing everything you can... great job! Thanks for answering all my questions, I have a clearer picture now. Your coop is new (which is pretty by the way) and you started with chicks, so I'm thinking maybe mites are not the problem. I think it usually takes a lot longer exposure to the environment for parasites to become a problem, and often times they arrive with "inherited" birds or old coops, not chicks and new lumber.
I missed this part the first time around:
I know one of my birds did not like dealing with the others' flapping at all so she just hopped down and waited until they finally settled, but by then it was too dark for her to make her way back up on her own, I had to lift her in place. Something similar happened another time with a different bird, only her best buddy (already on the roost) couldn't stand to be without her so she jumped down on the floor to be with her. Both those observations happened while my girls were still learning the ropes, but now everyone has their place and routine figured out.
Anyway, just wondering if maybe lowering the roosts might help. Also, 9 full size chickens seems like a lot to keep in only 80 SF of space. I know it's not what you want to hear, but eventually you may have to downsize a couple birds. Though lowering the roosts to just 5-6" off the floor could work. Remember, it's not only about how sleeping birds fit on the bars, it matters how they get up there, and how they jump down without crashing into walls.
I missed this part the first time around:
Did this happen still during daylight or was it dark? Even in dim light, chickens don't see well and aren't comfortable moving around even though you can still see perfectly fine. I'm just trying to think of anything here, throwing out ideas. Also...And now they stopped going up into the coop and they've stopped laying. I tried herding them up there, which is no small feat, and shut the door to lock them in. I checked them later and they were huddled at the door on the floor instead of roosting. I thought that might be more stressful than just leaving them alone so I didn't herd them more than once. I did try coaxing them with treats and only 3 of them ventured up, ate treats, and went back down.
How high are the roosts from the coop floor? If they have to use their wings to fly up there, that takes a lot of space, a good 20" or more per bird while settling. After they settle, they'll scoot closer together and it seems like there's plenty of room to spare. It's possible that while some of your birds get to the roosts fine, others flap up there and knock over (or annoy) the first ones, or there's too much scuttling going on and they just jump down. Have you watched what they do through a window?I can't see the perches without a whole lot of trouble, they are too high.
I know one of my birds did not like dealing with the others' flapping at all so she just hopped down and waited until they finally settled, but by then it was too dark for her to make her way back up on her own, I had to lift her in place. Something similar happened another time with a different bird, only her best buddy (already on the roost) couldn't stand to be without her so she jumped down on the floor to be with her. Both those observations happened while my girls were still learning the ropes, but now everyone has their place and routine figured out.
Anyway, just wondering if maybe lowering the roosts might help. Also, 9 full size chickens seems like a lot to keep in only 80 SF of space. I know it's not what you want to hear, but eventually you may have to downsize a couple birds. Though lowering the roosts to just 5-6" off the floor could work. Remember, it's not only about how sleeping birds fit on the bars, it matters how they get up there, and how they jump down without crashing into walls.