I just purchased your Alexa theme, and upon installation a noticed the notification below.
Your theme (Alexa) contains outdated copies of some WooCommerce template files. These files may need updating to ensure they are compatible with the current version of WooCommerce. You can see which files are affected from the system status page. If in doubt, check with the author of the theme.
When I view the system status page, it shows the below results.
alexa/woocommerce/single-product/add-to-cart/variable.php version 2.5.0 is out of date. The core version is 3.0.0.