Slider not working for several Browsers

Hi there..

First of all, your slider is great.. very easy to use and very fast perfomance! ??

But i have a little Issue..
The Slider works great for me in Chrome but not in Firefox, Edge or on my mobile phone via Safari…
On these Browsers, i can just see the first image of the slider and no arrows or something to slide trough the slider…

Hope you understand what i mean..

My site: Vapers-only.de

The page I need help with: [log in to see the link]