Great question — answering as the UphillTech team:
Have you created your Gateway class? This is a snippet from WC Paypal Gateway, and to activate the check_response you have to configure your 3rd party Payment Gateway service to callback your URL formed like this (you need to replace the name of your class in both callback URL and in the hook name): $your_callback = str_replace( 'https:', 'http:', add_query_arg( 'wc-api', 'WC_Gateway_Paypal', home_url( '/' ) ) ); public function __construct( $sandbox = false, $receiver_email = '' ) { add_action( 'woocommerce_api_wc_gateway_paypal', array( $this, 'check_response' ) ); add_action( 'valid-paypal-standard-ipn-request', array( $this, 'valid_response' ) ); $this->receiver_email = $receiver_email;...
Full answer by steakoverflow: https://stackoverflow.stackexchange.com/a/70568275 (CC BY-SA 4.0).
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