Product with custom Price table hangs on saves

I have added following fields to commerce product type of "product"

1. Maturity (Taxonomy, set to Product Attributes): has value of Adults, Children
2. Room (Taxonomy, set to Product Attributes): has value of Double, Single
3. Price dates (type of Date with End date required)
4. Price table (Commerce product price table, unlimited)

I've modified the public function defaultFields($bundles) in inline_entity_form/includes/commerce_product.inline_entity_form.inc to show dates and price table:

  public function defaultFields($bundles) {
    $fields = array();
    $fields['title'] = array(
      'type' => 'property',
      'label' => t('Variation title'),
      'visible' => TRUE,
      'weight' => 1,
    );
	
    $fields['sku'] = array(
      'type' => 'property',
      'label' => 'Price code',
      'visible' => TRUE,
      'weight' => 2,
    );

    // If only one product type is allowed, its fields can be used as columns.
    if (count($bundles) == 1) {
      $bundle = reset($bundles);
		$image_added = FALSE;
		$hide_default_price = FALSE;	// hide default Commerce price
      foreach (field_info_instances('commerce_product', $bundle) as $field_name => $instance) {
        $field = field_info_field($field_name);

        // If the product has an imagefield, show it.
        switch ($field['type']){
			case 'image':
				if(!$image_added){
					$fields[$field_name] = array(
						'type' => 'field',
						'label' => $instance['label'],
						'formatter' => 'image',
						'settings' => array('image_style' => 'thumbnail'),
						'delta' => 0,
						'visible' => TRUE,
						'weight' => -10,
					);
				}
				// Don't add any other imagefields. One is enough.
				$image_added = TRUE;
				break;
			case 'datetime':
				/*	Add field date	*/
				$fields[$field_name] = array(
					'type' => 'field',
					'label' => $instance['label'],	//t('Date'),
					'formatter' => 'date_default',
					'settings' => array('format_type' => 'short'),
					'visible' => TRUE,
					'weight' => 80,
				);
				break;
			case 'commerce_price_table':
				/*	Add field field_price_table */
				$fields[$field_name] = array(
					'type' => 'field',
					'label' => $instance['label'],
					'formatter' => 'commerce_multiprice_default',
					'settings' => array(),
					'visible' => TRUE,
					'weight' => 90,
				);
				if($instance['settings']['commerce_price_table']['hide_default_price'] == 1){
					$hide_default_price = TRUE;
				}
				break;

        }
      }

      // If the type has up to 3 attributes, show them instead of the title field.
      $attributes = $this->attributes($bundle);
      if (count($attributes) <= 3) {
        $fields['title']['visible'] = FALSE;

        foreach ($attributes as $field_name => $attribute) {
          $field_type = field_info_field_types($attribute['field']['type']);
          // Override the default formatter for taxonomy_term_reference.
          if ($field_type['default_formatter'] == 'taxonomy_term_reference_link') {
            $field_type['default_formatter'] = 'taxonomy_term_reference_plain';
          }

          $weight = -3;
          $fields[$field_name] = array(
            'type' => 'field',
            'label' => $attribute['instance']['label'],
            'formatter' => $field_type['default_formatter'],
            'settings' => array(),
            'visible' => TRUE,
            'weight' => ++$weight,
          );
        }
      }
    }

	

	if(! $hide_default_price){
		$fields['commerce_price'] = array(
			'type' => 'field',
			'label' => t('Price'),
			'formatter' => 'commerce_price_formatted_amount',
			'settings' => array(),
			'visible' => TRUE,
			'weight' => 99,
		);
	}
    
    $fields['status'] = array(
      'type' => 'property',
      'label' => t('Status'),
      'visible' => TRUE,
      'weight' => 100,
    );

    return $fields;
  }

The inline entity form displays as I expect, but when I add a new variation, the Save is pending forever.
I figure out that the issue is caused by price table because if I show dates only, the Saving task works well.