Direct Connect not showing metric data even when the direct connect is turned off manually?

I have create an alarm for direct connect with ConnectionState metric and dimension set to connection id.

It is showing ok state in alarm.

Now, when Direct Connect turned off for maintenance activities, still the alarm is not triggered.

So, when I check the metric graph, it is showing value 1 only in the metric graph in the time duration when direct connect is turned off.

Why it is not showing in metrics even the direct connect turned off?

I used metric as below terraform code.

metric_query {
    id                = "dx1"
    label             = "DX State"
    account_id        = var.account_id
    return_data       = "true"

    metric {
      metric_name     = "ConnectionState"
      namespace       = "AWS/DX"
      period          = "300"
      stat            = "Average"

      dimensions = {
        ConnectionId  = var.connection_id
      }
    }
  }