If orders are not being marked as completed automatically, there are a few key areas to inspect within your configuration:
First, check your order autocomplete condition by navigating to WooCommerce > Settings > Autocomplete Orders. For example, if you’ve chosen to autocomplete only virtual products, ensure that the test orders meet those conditions. A mismatch here will prevent the order from being marked as completed.
Also, verify that the payment gateway used in the order is not listed under the Excluded Gateways setting. If a gateway is excluded, any order using it will not be autocompleted, regardless of other settings.
Lastly, confirm that the order status is eligible. Autocompletion only works for orders that are successfully paid or meet the specified conditions in your settings.
If everything seems correct but issues persist, try clearing any caching plugins and testing the plugin in a staging environment to rule out conflicts with third-party extensions or custom code.