Profile: kelvinL-2

Problem: I would like to show the post excerpt if it is not empty, otherwise show the full post content.

Solution:
The wpv-post-excerpt shortcode utilizes WordPress's the_excerpt function to display a post excerpt. This means that you cannot expect wpv-post-excerpt to be empty if the post contains any content. Instead, you could add this custom shortcode to your child theme's functions.php file:

add_shortcode('wpv-post-real-excerpt', 'real_excerpt_shortcode');
function real_excerpt_shortcode() {
  global $post;
  return $post->post_excerpt;
}

Go to Toolset > Settings > Frontend Content and enter "wpv-post-real-excerpt" in the 3rd party shortcodes area. Then you should be able to test the excerpt like this:

[wpv-conditional if="('[wpv-post-real-excerpt]' != '')"]
[wpv-post-excerpt]
[/wpv-conditional]
[wpv-conditional if="('[wpv-post-real-excerpt]' != '')" evaluate="false"]
[wpv-post-body view_template='None']
[/wpv-conditional]

Relevant Documentation:
https://developer.wordpress.org/reference/functions/the_excerpt/
https://toolset.com/documentation/user-guides/views-shortcodes/#wpv-post-excerpt