Why doesn't the animateOut property work?

Question

css

animateIn works but animateOut doesn't. I still don't understand how to solve this problem. And the speed of the fade effect is not adjusted.

If you remove the animate property, then it slides normally and the speed is adjusted.

$(".hero__slider").owlCarousel({
  animateIn: 'fadeIn',
  animateOut: 'fadeOut',
  dots: true,
  dotsContainer: '.hero__dots',
  items: 1,
  nav: true,
  navContainer: '.hero__nav-content',
  navSpeed: 1500,
  navText: [],
  mouseDrag: false,
  paginationSpeed: 1500,
  smartSpeed: 1500,
  touchDrag: false
});