Why doesn't Slick slider work with Fancybox?

Question

JavaScript

I tried to connect Slick slider with Fancybox (Fancybox is already used on the project, so I did not drag another plugin). The result does not work correctly: when a popup appears, some empty space appears in the slider. I can not make out the reason, there are no errors in the console. Maybe there is a similar example, I couldn't find it anywhere.
Fancybox code:

$('.js-fancybox').fancybox({
         openEffect  : 'none',
         closeEffect : 'none',
         prevEffect : 'none',
         nextEffect : 'none',
         closeBtn  : true,
         arrows    : false,
         nextClick : false,
         helpers : {
          title : {
           type : 'inside'
          },
          buttons : {},
          thumbs : {
           width : 50,
           height : 50
          }
         },
         afterLoad : function() {
          this.title = 'Image ' + (this.index + 1) + ' of ' + this.group.length + (this.title ? ' - ' + this.title : '');
         }
      });

Fiddle .