I'am using magento 2.1.3 and have a problem with amount of items displayed in the categories. When I save my category everthink works fine and all of the 64 are shown in the category. But when I reindex at night the amount of displayed items is smaller. I can see that catalog_category_product_index is missing some of the products. When I save the category the amount of items increases and everthink is fine.