Ok so I had an interesting experience watching the pullet in question drop her 12th egg (yay her first dozen!).
The minute before she laid, she kept trying to get under the head hen like a chick! I wish I had my phone on me then. She was repeatedly tunnelling her head between the head hen's legs, who was having none of it. Finally, she puffed up like a very sick hen, tail down, and laid. Seems like she was reverting to seeking maternal comfort because she was in pain
Prior to that, she went in and out of the nesting boxes, which is promising. But seems like she has no idea what's going on yet!