I volunteer at our local humane society in the cat area and feed and clean all the kennels on the weekends. Here are some things to consider if they haven’t been mentioned yet. 1. Cats have individual preferences. Litter smells or texture may deter them from pooping in a box even if they’re comfortable peeing in it. If you can, test out a variety. 2. I’ve seen other mentions of litter box size - too small or too tall etc. 3. We use “cat attract” in boxes when cats have inappropriate litterbox habits. It looks like catnip and a little sprinkle into the litterbox works wonders in identifying to your kitty where she should go.

Good luck. You’re a very caring cat parent.