Why doesn't owl see the items in the function?

Question

Owl Carousel

Hello, I have this code

var storiesItems = $('.stories-items');

  storiesItems.owlCarousel({
    items: 1,
    dots: false,
    nav: true,
    onInitialize: callback
  })

  function callback(event){
    var items  = event;
    console.log(items)
  }

The output in the console is 0. Despite the fact that the slider works from here and it has 4 elements