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

on our website germansherpa.com 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.

Hi,

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.