If its a set back, I would say its a minor one. A lot of the cats at the shelter sit in their litter boxes and Hermoine did it last night when we first brought her home.

Minnie will remember her comfy bed and rug soon.

Not sure if you have tried this...but I've read on here a lot that classical music is calming to cats. I've actually never tried it until yesterday on the way home from the white coats for Micah.

He wanted out of his port-o-prision so badly. I asked David what classical station came in in our area and as soon as it was on, Micah laid down and shut his eyes. I was blown away!!! It works.

Maybe you could play some music in Minnie's room??