This issue occurs if you create a custom page or if you create your own theme . I found the people experiencing the same issue here and here. CSS Style WooCommerce but the problem can be solved easily
Add Class woocommerce
Solved, WooCommerce CSS Style not working by adding class ‘woocommerce’ inside <body> tag. I get it from github users Manovotnni , you can read more details here. Now open the header file in your theme and find the <body> change to
<body <?php body_class( 'woocommerce' ); ?>>
This method works well for each custom page.