"Angent is inavailable" at dashboard in last 20 issues section

[qwertys1]

Hi,
I have a problem with my trigger message in "Last 20 issues" section. Message was triggered when server was power on, but I power off this server and the trigger message still exist on my dashboard with question mark (when I point on it I receive message "Agent is unavailable"):


What I must do to erase this trigger message from my last 20 issues when server are down? Ack is not a solution for me.

[BDiE8VNy]

Try to open the corresponding trigger configuration (if provided by template, within the template) and save it without changing anything.
If the trigger expression is based on existing data, it might be necessary to clear item data first.

[qwertys1]

Thanks BDiE8VNy!
Saving without changing works for me (even without clear item history).

Question is: is this bug or a feathure?