Error viewing plugin Activity Log

I’m seeing the error below when selecting Activity Log in plugin version 4.1. Any ideas?

Thanks,
Joel

KWSConstantContact::getList: Exception
WP_Error Object
(
    [errors] => Array
        (
            [504] => Array
                (
                    [0] => Gateway Timeout
                )

        )

    [error_data] => Array
        (
            [504] => Array
                (
                    [0] => stdClass Object
                        (
                            [error_key] => mashery.gateway.timeout
                            [error_message] => A gateway timeout error was encountered while processing this request.
                        )

                )

        )

)

https://www.ads-software.com/plugins/constant-contact-api/