kepkame

Получил ответ на другом форуме. Настройка afterClose не понадобилась, я совсем не в ту сторону копал.

var fancyElements = jQuery.map(jQuery('.product-gallery__item a'), function(el) {
      return{
      src: el.href,
      caption: el.title
     }
    });

jQuery(".product-gallery__wrapper").slick({
  slidesToShow: 1,
  slidesToScroll: 1,
  infinite: false,
  centerMode: false,
  focusOnSelect: true,
  asNavFor: '.gallery-thambnails'
});

// Highlight thumbnail if large image is the same
jQuery(".gallery-thambnails").on("afterChange", function(event, slick, currentSlide, nextSlide) {
  // remove all active class
  jQuery(".gallery-thambnails .slick-slide").removeClass("slick-current");
  // set active class for current slide
  jQuery(".gallery-thambnails .slick-slide:not(.slick-cloned)").eq(currentSlide).addClass("slick-current");
  jQuery("#wcOpenFullPhoto").data("order", currentSlide);
});

jQuery(".gallery-thambnails").slick({
  slidesToShow: 4,
  slidesToScroll: 1,
  infinite: false,
  dots: false,
  centerMode: false,
  focusOnSelect: true,
  asNavFor: '.product-gallery__wrapper'
});

jQuery('#wcOpenFullPhoto').on('click', function(e) {
  e.preventDefault();
  jQuery.fancybox.open(
    fancyElements, {
      // Custom options
      loop: false,
    },
    jQuery("#wcOpenFullPhoto").data("order")  // Start gallery from selected index
  );
});