I am running the Smartmag theme on my website https://fuxwithit.com/. I have been running it as a blog for years. I recently set up a store to sell merchandise using woocomerce - https://fuxwithit.com/shop/.
There is a bug with the site though. When a user tries to buy an item that comes in different sizes, the size data does not add to cart. So when the user checks out the size is not included and the order can’t be fulfilled.
I spoke to support at woocomerce/wordpress and they said this is likely a theme issue. My theme is up to date but they instructed me that there are outdated template files. See details below. They said I should reach out to theme creator for assistance.
Theme
Name: SmartMag
Version: 2.5.2 Author URL: http://theme-sphere.com
Child Theme: 
– If you are modifying WooCommerce on a parent theme that you did not build personally we recommend using a child theme. See: How to create a child theme WooCommerce Support: 
Templates ### Archive
Template: Your theme has a woocommerce.php file you will not be able to override the woocommerce/archive-product.php custom template since woocommerce.php has priority over archive-product.php. This is intended to prevent display issues.
Overrides: smart-mag/woocommerce/loop/orderby.php version - is out of date.
The core version is 3.6.0 smart-mag/woocommerce/loop/pagination.php version - is out of date.
The core version is 3.3.1 smart-mag/woocommerce/single-product/short-description.php version - is out of date.
The core version is 3.3.0 smart-mag/woocommerce/single-product/tabs/description.php version - is out of date. The core version is 2.0.0