SamK

I believe you said in your original post that it had been recently planted ( a few weeks ? ). The soil mixture sounds really good... the level of light is fine.. the water seems adequate ( mine get watered a minimum of every other day ). It could simply be "shock" from being transplanted and possibly from moving from a lower light level to a higher light level. I'd give it time.. and possibly some more water ( every other day ). Bananas need a lot of organic matter and a lot of water.. I've had some that did that initially, but after a few weeks perked right up. The plants will first put out roots before new growth as long as it has sufficient leaves for photosynthesis.. so, although you may not see growth "top side" as long as the center leaf looks healthy; you are likely getting foundational growth on the "bottom side" ( roots ).