I skimmed back, forgive me if I missed it, and didn't see this info:
How many birds?
How much roost length?
Age of birds...are all bird the same age and raised together?
Did you put them on roost after dark? That will work best, if it's good and dark they should stay on roost.
Hmm.... summer...
LOL!
I put a hinged plywood cover on my nest bank that covers the nest openings and the perch in front of them,
put it down late in the afternoon after laying is done then open in it back up after dark when I lock up the coop.
Works a charm! Only need it when integrating new pullets.