Some hens can be like that. And it's so hard introducing new chickens to each other. I have one like that. She is an older one, though. I just keep picking her up and/or giving her a tap on the back of her neck with my fingers (kinda like when a chicken pecks another), trying to show her I am...
You have done a thorough job! You have checked everything and did everything I would have done. I guess I would have to say she could be lonely and missing her sister. :( They become attached to each other so much. When the time is right and they get to be reunited, I say she will come around...
It is early! :0 Especially since I have a crowning rooster already. Usually the new rooster waits awhile. This one is living up to the Cocky syndrome, down to a T! Lol I hope my Wyandotte isn't going to be mean like my last one. :| He didn't crow until 17 weeks, so maybe they will be different...
Yay!! I hope there are babies in the near future!!! :weee
And maybe you will hear a crow soon! My banny crowed at 7 weeks, and I caught my 10 week old Wyandotte Rooster crowing today :D
I am sorry to make a comment without any other solution, but it seems like you have tried everything I would try. Sorry this is happening to your flock :( It's always hard to go through this when we tried and have done everything we could. :hugs I wish I had some answers for you.
Oh, and he will let us pick him up and cuddle for a second ;) My son would carry him on his shoulder for about 2 minutes before he was ready to fly off.