no image with new version of woocommerce

in particolar, i think the problem is here in this part of functions.php in the plugin folder:

// Returns the Featured Image associated to a specific Product
function woo_ce_get_product_assoc_featured_image( $product_id = 0 ) {

$output = ”;
if( $product_id ) {
$thumbnail_id = get_post_meta( $product_id, ‘_thumbnail_id’, true );
if( $thumbnail_id ) {
$thumbnail_post = get_post( $thumbnail_id );
if( $thumbnail_post )
$output = $thumbnail_post->guid;
}
}
return $output;

}

ANY IDEAS?

THE STRANGE IS:

if i manually add a product it export the image path

if i use csvi import deluxe or just csvi import doesen’t export the image path even if the image is properlt sets as featured image

BOH?!??