Consider putting them in a smaller enclosure for a while, or blocking off part of their enclosure so they can't run away from you. If you work with them daily, handle them several times a day whether they want to be picked up or not, calmly and slowly, they will soon lose their fear. I pick them up to eye level, look them in the eye from the side, and talk to them calmly for a while. This calms them down. Once we make eye contact, and talk for a bit, they seem to be more open to the idea that I'm not a predator. [I am actually a predator, but I'm not going to eat them for a while yet, so no need for them to worry about it every time I appear.]
I processed 21 CX in March, and am growing out 5 ginger broilers now. The CX didn't run from me at all. i had to physically push them out of the way to do anything in the brooder. The ginger broilers however ran away like normal chickens. I haven't focused on handling a whole lot, since they'll be dinner soon, but I have done it a bit since I want them not to attack me or panic when I do health inspections. My eggers get individual attention several times a day. If we can't get to be friends, they find new homes. Life's too short for chickens that bite or persist in thinking I'm terrifying. I've only had a few like that.