Hello (again) :-) one hosts has an (achknowledged) Alarm in Nagios, and one Check_MK service which has an open critical state. The Host and Service are only visible in the "Show all" section. I also tried to add that host in the "Critical Items" List but same behavior. Is that the normal behavior, maybe due to the ACK of the Alarm? If yes, that would be not that good ;) Cheers!