Unable to get a slide show working

After upgrading from Drupal 8.2 to 8.4, my slide show stopped working (Slick Carousel)
It had become invisible.

After trying to fix it all day, I decided to give up and try another module:
https://www.drupal.org/project/views_slideshow

With this one, i do manage to get images showing. The image is stuck on the first slide though.
In the Views Preview, it works fine (as does the slick carousel in Views Preview)

What could be the problem?

The site I’m working on:
http://www.stcaecilia.com

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/22/feed