Behavior/texture packs not working on custom worlds

So basically, I have bought the "Advanced Dragons" pack on the store, and the Texture and behavior pack only works in the world that came with it, i doesnt work on any other world, it doesn't show up. Im not 100% sure if it is a bug, but since it works on different versions, such as mobile, im guessing that it is a bug. There are no reproduction steps, it just happened as i bought it.