source/php/PostTypes/Events.php
public function getUserGroups($value, $post_id, $field)
    {
        if (!empty($value)) {
            \EventManagerIntegration\App::importPublishingGroups();
        }

        return $value;
    }
public function getUserGroups($value, $post_id, $field)
    {
        if (!empty($value)) {
            \EventManagerIntegration\App::importPublishingGroups();
        }

        return $value;
    }
Import user groups when saving settings
@param  string $value   the value of the field
@param  int    $post_id the post id to save against
@param  array  $field   the field object
@return string          the new value