It is normal for many breeds where mother or rooster does not promote younger birds roosting up. For me it is unacceptable since makes so rapid counting at night is not possible and otherwise dumb predators like opossums can catch birds.
Heat conservation is likely first concern. Under natural conditions (as jungle fowl) some protection from some predators may also be realized. Your chickens likely consider themselves jungle fowl.
The birds in question are not hens yet. Many will not go to roost until 12 or more weeks of age.
To be called hens the birds must at least be to point where eggs are produced and with some the birds must be either a year old or have gone through a molt after becoming a adult.
Advice above all good. Additionally I would confine juveniles to coop for a few days and release them late in evening so they will want to go to roost shortly after coming out when memory still fresh. Problem, if works is an imprinting issue.