i had a rooster and 3 hens that insisted on sleeping the floor for a few months and one day..viola.....they were all on the roost. I have no insight as to why but perhaps give it some more time.
I too had this just happen. Found a dead hen (not sure what acutally happened to her) and then another with her neck scalped... put her is isolation to heal up. After she was reintroduced to the flock same thing happened again. I dont know why he keeps attacking her. He was also pretty...