I have a custom post type leistungencpt with categories. Now I`m planning to show all posts from this CPT but from an certain category of this CPT with an shortcode.

My code

function my_custom_sliderlesoftware( $atts, $content = null ) {
 
 
    /* Turn on buffering */
    ob_start(); 
    
    $anzahl = shortcode_atts(array(
    'anzahl' => '#',
    ), $atts); 
    
 
 
    $args = array( 
    'post_type' => 'leistungencpt',
    'product_cat' => 'le-software-entwicklung',  
    'posts_per_page' => $anzahl['anzahl'],
    'facetwp' => true   ,
    );
    $query = new WP_Query( $args );
    
?>
<div class="post_box"> 
<?php if ( $query->have_posts() ) : while ( $query-> have_posts() ) : $query-> the_post(); ?> 
     
                <div class="vc_col-sm-4 post_boxinner"> 
                    <div class="post_img"> 
                    <a href="<?php the_permalink() ?>" title="<?php the_title(); ?>"><?php echo get_the_post_thumbnail( get_the_ID(), 'startgrid' ); ?></a>
                    </div> 
                    <h3 class="post_headline"><a href="<?php the_permalink() ?>"><?php the_title(); ?></a></h3>  
                    <p class="post_excerpt"><?php
                    echo wp_trim_words( get_the_excerpt(), 22, ' […]' );
                        ?></p> 
                    <div class="vc_btn3-container vc_btn3-left vc_do_btn">
                    <a class="vc_general vc_btn3 vc_btn3-size- vc_btn3-shape- vc_btn3-style-btn btn-rahmen vc_btn3-color-green" href="<?php the_permalink() ?>" title="Weiterlesen">Weiterlesen</a>
                    </div>
                </div> 
        

<?php 
    endwhile;
    wp_reset_postdata(); // this should be inside if - there is no need to rested postdata if the_post hasn’t been called.
    endif; 
?>
</div>

    <?php
    /* Get the buffered content into a var */
    $sc = ob_get_contents();

    /* Clean buffer */
    ob_end_clean();

    /* Return the content as usual */
    return $sc;
}

add_filter('widget_text','do_shortcode');

How is the right loop for all posts in certain category from the CPT leistungencpt?

I have tried many ways, but nothing is happening, no posts will show up in the frontend.