I've defined an action to notify administrators for active problems with a step 1-0 in order to get notifications until the problems exist. There is a condition 'Event acknowledged = "Not Ack"' .

In normal period, if a problem occurs, when I acknowledge it, I don't receive notifications anymore for it, that's good.

But if an event occurs during a maintenance period and if this period stops being active, when I acknowledge the issue, notifications are sent forever. Acknowledgement is shown on the GUI but it has no effect on actions/operations.