Slideshow unable to add images in 3.6

When adding images to slideshows in a multisite/subfolders install only an empty box with no image shows up in the admin panel. When turning debugging on, I get this message:

Notice: wpdb::escape is deprecated since version 3.6! Use wpdb::prepare() or esc_sql() instead. in /home/users/xxx/test2/wp-includes/functions.php on line 2871

However, on the plugin page on wordpress.org several people claim that the plugin works under 3.6.

I use the lates plugin version 2.2.11

http://wordpress.org/plugins/slideshow-jquery-image-gallery/