I've noticed some parameters incorrectly used in your shortcode, the
thumbnail_url can only be used in combination with
thumbnail_custom and its value must be the URL address of your custom thumbnail. I think you meant to use:
thumbnail_class=center, the excerpt_length was declared twice.
display_content=false parameter don't need to be declared as it's false by default.
Try with this one:
As you choose "number_posts=1" it will display only one post from blog ID 17, in theory this new shortcode should work.
Please, let me know if this solve the issue.