I had several problems with the woocommerce categories but managed to solve them. All but one.

The category images are not displayed

This is what debug shows:

Notice: Trying to get property of non-object in /public_html/wp-content/themes/scalia/inc/woocommerce.php on line 363

function scalia_woocommerce_subcategory_thumbnail( $category ) {

$small_thumbnail_size = apply_filters( 'single_category_small_thumbnail_size', 'shop_catalog' );
$thumbnail_id = get_woocommerce_term_meta( $category->term_id, 'thumbnail_id', true);
$image = '';

if ( $thumbnail_id ) {
$image = wp_get_attachment_image_src( $thumbnail_id, $small_thumbnail_size );
$image = $image[0];
}

if ( $image ) {
$image = str_replace( ' ', '%20', $image );
echo '<img src="' . esc_url( $image ) . '" alt="' . esc_attr( $category->name ) . '" class="img-responsive" />';
} else {
echo wc_placeholder_img($small_thumbnail_size);
}
}

Thank you.

Problem is resolved.