Well, it seems clear that, at $190m, the movie was way overbudgeted: its Playmobil/shiny medieval aesthetic makes it look like a Narnia movie, but without that cultural brand, and the Jack and the Beanstalk fairy-tale source is surely snicker-inducing to teens.
That said, a mid-August release might have been better: still in the summer, but after the big blockbusters have come and gone.