The few who are shunning the coop are probably getting sick and tired of being knocked off perches that are only able to accommodate some of the flock, not everyone. Only the most assertive chickens will be up to the competition for roosting space. The more timid ones will avoid the conflict and find an alternative.
If you were to watch the chickens trying to get settled on the perches, you would see they need more than a foot of linear space to fly up. With a foot or less, flapping wings are likely to knock off the perch those already up and trying to settle in. Tempers flare up creating a dysfunctional environment.
Before you try to force the outliers back into the coop, you need to expand the roosting space. It's always preferable to err on the side of too much space than trying to fit the maximum number into the bare minimum.
After you expand roosting space, block off the goat roof. Chickens will do anything to avoid change so the only way is to make it impossible to access an area where you don't want them.
