If you encounter issues with the Best Seller sorting option, follow the below steps to troubleshoot the problem.

Step 1. Confirm the existence of placed orders on your instance. Bestsellers sorting depends on product sales, so to populate the 'amasty_sorting_bestsellers' table, orders must be generated in your Magento.  Also keep in mind that the extension prioritizes sorting based on the quantity sold, without considering monetary revenue.

Step 2. If applicable, ensure that there are orders placed in your Magento that correspond to the Bestsellers Period (days) and Exclude Orders Status settings:

Step 3. Ensure that you are testing the Best Sellers sorting option from the store view that corresponds to the same scope where the order with the product was placed. Currently, the Bestsellers statistics operate on a store-wise basis.

Step 4. Make sure that the Bestseller option is set to display ascending or descending results according to your expectations. Proceed to Stores → Configuration → Amasty Extensions → Improved Sorting → General tab. Check the Best Sellers option in the Sort Attributes Descending by Default setting.

Select the option in the field if you wish to display it with descending results by default. Conversely, leave it unselected to show ascending results.

Step 5. If the extension settings are correct, but the issue persists, it's required to check the Magento reports. To check if the sorting by Bestsellers is working correctly, please follow these steps:

php bin/magento indexer:reindex && php bin/magento cache:flush

Step 1. Confirm that your custom attribute is set up correctly and assigned to the products. Consult our user guide to verify the steps of creating a custom attribute.

Step 2. Check if the attribute selected in the Custom Bestsellers Attribute setting is accurate: