Layer Slider Enfold Theme - One Layer (Picture) is shown on desktop but not on mobile

on our website we have various layer sliders.
There is on the left side our logo over the pictures / videos shown.

On desktop this works fine.
On mobile you only see a frame with a ? on it.

How can we solve this?
Thanks for your support.


Contact with your purchase item author @Kriesi right here as a comments

hope they will help

Tried this already - I signed for their support but in the forum there is not button anywhere to create a new topic.
Only link I found led me here.