I used the following PHP code to invite. This worked prior to update, but I'm including it in case there is a problem with the way I'm doing things now in 2.05.

$participant_data_array[] = array(
'email' => $add_user['email'],
'lastname' => $add_user['last_name'],
'firstname' => $add_user['first_name'],
'attribute_1' => $add_user['class_title'],
'attribute_2' => $add_user['class_date'],
'attribute_3' => $add_user['class_presenter'],
'attribute_4' => $add_user['class_obj1'],
'attribute_5' => $add_user['class_obj2'],
'attribute_6' => $add_user['class_obj3'],
'attribute_7' => $add_user['class_id'],
'attribute_8' => $add_user['user_id']
);

try {
$participants = $myJSONRPCClient->add_participants($sessionKey, $this_survey_id, $participant_data_array, true);
} catch (Exception $e) {
die('Caught add_participants exception: ' . $e->getMessage());
}