orm模型观察者无效

# 模型关键代码
public static function boot()
{
  parent::boot();
  static::observe(ConfigObserver::class);
}

# 观察者代码
class ConfigObserver
{
    public function created(Config $config)
    {
        Log::channel('common')->info('config created');
    }

    public function updated(Config $config)
    {
        Log::channel('common')->info('config updated');
    }

    public function deleted(Config $config)
    {
        Log::channel('common')->info('config deleted');
    }

    public function forceDeleted(Config $config)
    {
        Log::channel('common')->info('config forceDeleted');
    }
}