SBaltz, I wonder if you were able to get any resolution to this issue or advice to share.
I have the same circumstances with one of my hens. I have checked multiple times for lice and mites, they have lots of different things to entertain them, free range, no roos, etc. My chicken (Georgia) is the lowest of the pecking order and I've seen the higher up ones peck at her when she goes for food if they're eating (so I provide multiple feed stations). But I wonder if it's happening more at night. I just bought "Pick-No-More" and am going to give that a go as well as upping the protein to 18%.