Cannot insert pictures into slider

Hi
I am trying to put a full width slider on to a none full width site.
I cannot get passed a problem where the widget does not respond to the button “insert into post” as I try to insert images.

When pressing the “insert into post” i return to the widget settings with no changes to image source. It does not help to enter the source manually.

Thanks for help

https://wordpress.org/plugins/so-widgets-bundle/