Thumbnail Slider doesn’t work

Hello.
So recently (when I updated the wordpress version) the slider of the YITH Zoom Magnifier stoped working, only the zoom is working and the pictures are displayed horizontal next to each other.
See what I’m talking about here: https://wrocksfootwear.com/product/jack-bluish-grey/

Can you help me? I want the thumbnail slider displayed.

Thank You.