This is good news!I have good news. Two days ago, I gave Raven an hour long bath. Then brought her outside to play with my other chickens and let everyone free-range. Every time her butt fell out, I caught her and pushed it back in. I did this for several hours. Her butt stayed in the entire night! And it's still in two days later. I still bring her in at night, and don't put her outside until the afternoon so she can rest and not lay eggs. I can't do that forever though, I wish there was an easy way to spay a hen.
Sometimes it takes a while for internal swelling to go down in order for the prolapse to stay in, regardless of the products you use, if there's no room, there's no room.
Your persistence, care and patience seems to have paid off. I hope it continues to stay in and she has no more problems.