So I ran into an issue where Yoast SEO was not auto-generating an excerpt for use within the Meta Description when a visual composer is being used. When I say visual composer I mean like Divi or WP Bakery Visual Composer. I was able to track down a filter that seems to have resolved the issue.
// FIX SEO incompatibility with visual composer add_filter( 'wpseo_replacements', function( $replacements ){ global $post; if( ! sizeof($replacements) && ! empty($post->post_content) ){ $replacements['%%excerpt%%'] = wp_html_excerpt( do_shortcode( $post->post_content ), 155 ); } return $replacements; });