I saw this but decided I didn't know enough about growing these inside to help you. I can say this though, they don't like as much water as many think, I'd let the soil get dry around it and see if that causes it to reach out more with roots. It looks like tiny roots forming on the picture but that could be debris from the potting soil. I hope you get some better advice, the plant is endemic here outside and I've only rooted long sections. For those, I stick them in soil but I let the soil get completely dry before I water again, otherwise they rot. Even when they are completely dry, I water sparingly. As well as liking less water than generally assumed, they like a lot more light than most people supply. Here they commonly grow in full morning sun and grow best in lots of light but not noon sun. I hope you can get this little cutie to root, and I hope someone steps in that can help you more.
