custom_gallery images not found

I’m trying to create a gallery from a Taxonomy Source.

I’ve created a custom Taxonomy for my images, which the Gallery shortcode recognizes when configuring it, but I get the error “custom_gallery images not found”

The only method that I seem to be able to create a gallery with, is adding images from the media library. All of the other sources seem to return the same error.

https://www.ads-software.com/plugins/shortcodes-ultimate/