OAuth error after saving token: “Missing required parameter: refresh_token”

After entering the Google Access Code and hitting the “Save” button, I get the following error message in the log:

26 May 2017 13:42:14 	 PHP 7.0.17Array
(
    [ERROR_MSG] => Error refreshing the OAuth2 token, message: '{
  "error" : "invalid_request",
  "error_description" : "Missing required parameter: refresh_token"
}'
    [TRACE_STK] => #0 [path removed]/wp-content/plugins/cf7-google-sheets-connector/lib/php-google-oauth/auth/Google_OAuth2.php(240): CF7GSC_Google_OAuth2->refreshTokenRequest(Array)
#1 [path removed]/wp-content/plugins/cf7-google-sheets-connector/lib/php-google-oauth/Google_Client.php(312): CF7GSC_Google_OAuth2->refreshToken(NULL)
#2 [path removed]/wp-content/plugins/cf7-google-sheets-connector/lib/google-sheets.php(50): CF7GSC_Google_Client->refreshToken(NULL)
#3 [path removed]/wp-content/plugins/cf7-google-sheets-connector/includes/class-gs-service.php(93): CF7GSC_googlesheet->auth()
#4 [path removed]/wp-includes/class-wp-hook.php(298): Gs_Connector_Service->cf7_save_to_google_sheets(Object(WPCF7_ContactForm))
#5 [path removed]/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters('', Array)
#6 [path removed]/wp-includes/plugin.php(453): WP_Hook->do_action(Array)
#7 [path removed]/wp-content/plugins/contact-form-7/includes/submission.php(162): do_action('wpcf7_mail_sent', Object(WPCF7_ContactForm))
#8 [path removed]/wp-content/plugins/contact-form-7/includes/submission.php(28): WPCF7_Submission->submit()
#9 [path removed]/wp-content/plugins/contact-form-7/includes/contact-form.php(647): WPCF7_Submission::get_instance(Object(WPCF7_ContactForm))
#10 [path removed]/wp-content/plugins/contact-form-7/includes/controller.php(58): WPCF7_ContactForm->submit(true)
#11 [path removed]/wp-content/plugins/contact-form-7/includes/controller.php(18): wpcf7_ajax_json_echo()
#12 [path removed]/wp-includes/class-wp-hook.php(298): wpcf7_control_init('')
#13 [path removed]/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters(NULL, Array)
#14 [path removed]/wp-includes/plugin.php(453): WP_Hook->do_action(Array)
#15 [path removed]/wp-settings.php(470): do_action('wp_loaded')
#16 [path removed]/wp-config.php(89): require_once('[path removed]/we...')
#17 [path removed]/wp-load.php(37): require_once('[path removed]/we...')
#18 [path removed]/wp-blog-header.php(13): require_once('[path removed]/we...')
#19 [path removed]/index.php(17): require('[path removed]/we...')
#20 {main}
)

Is that due to a change in Google’s OAuth2 authentication perhaps?