The problem is facebook has set a five second timeout on their access token request. The request times out and the form values are not saved.
I fixed this by increasing the timeout to 10 seconds.
The code can be found on line 234 in:
facebook/includes/facebook-php-sdk/class-facebook-wp.php
try {
$response = self::handle_response( wp_remote_get( self::$DOMAIN_MAP['graph'] . 'oauth/access_token?' . http_build_query( $params, '', '&' ), array(
'redirection' => 0,
'httpversion' => '1.1',
'timeout' => 5,
'headers' => array( 'Connection' => 'close' ),
'user-agent' => self::generate_user_agent()
) ) );
} catch( WP_FacebookApiException $e ) {
return '';
}
I just replaced the ‘timeout’ value of 5 with a larger number.