Hello, Mady,
Thank you for getting in touch with us.
1/ As we can see, you are using CDN, please try to clear the CDN cache and check the slider from mobile then.
Let us know the result.
2/ We would recommend do not activate “Mobile Optimization” in Theme Options > General, in your case.
Also, when you resize the Google Chrome window, do not forget to re-fresh the page.
Kind Regards,
8theme team