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
);
});