Stop strip_shortcodes() stripping content inside shortcodes

Try the filters in your functions.php:

add_filter( 'the_excerpt', 'shortcode_unautop');
add_filter( 'the_excerpt', 'do_shortcode');

Props: @bainternet (Source)

Or, use your own filter on get_the_excerpt. Put this in your theme’s functions.php:

function custom_excerpt($text="") {
    $raw_excerpt = $text;
    if ( '' == $text ) {
        $text = get_the_content('');
                // $text = strip_shortcodes( $text );
        $text = do_shortcode( $text );
        $text = apply_filters('the_content', $text);
        $text = str_replace(']]>', ']]>', $text);
        $excerpt_length = apply_filters('excerpt_length', 55);
        $excerpt_more = apply_filters('excerpt_more', ' ' . '[...]');
        $text = wp_trim_words( $text, $excerpt_length, $excerpt_more );
    }
    return apply_filters('wp_trim_excerpt', $text, $raw_excerpt);
}
remove_filter( 'get_the_excerpt', 'wp_trim_excerpt'  );
add_filter( 'get_the_excerpt', 'custom_excerpt'  );

This will allow shortcodes in the_excerpt().

Props to @keesiemeijer (source)