Meanwhile on Icinga2 2.11 but the same problem still exists; notification is sent during downtime:
Service Object:
Object 'cla005!Service MyService' of type 'Service':
% declared in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 4:1-4:63
* __name = "cla005!Service MyService"
* check_command = "nscp"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 7:3-7:24
* check_interval = 60
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 20:2-20:21
* check_period = "24x7"
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-base-template.conf', lines 11:2-11:22
* check_timeout = null
* command_endpoint = ""
* display_name = "Service MyService"
* enable_active_checks = true
* enable_event_handler = true
* enable_flapping = false
* enable_notifications = true
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 23:2-23:25
* enable_passive_checks = true
* enable_perfdata = true
* event_command = ""
* flapping_threshold = 0
* flapping_threshold_high = 30
* flapping_threshold_low = 25
* groups = [ ]
* host_name = "cla005"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 4:1-4:63
* icon_image = ""
* icon_image_alt = ""
* max_check_attempts = 3
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 22:2-22:23
* name = "Service MyService"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 4:1-4:63
* package = "_etc"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 4:1-4:63
* retry_interval = 30
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 21:2-21:21
* source_location
* first_column = 1
* first_line = 4
* last_column = 63
* last_line = 4
* path = "/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf"
* templates = [ "Service MyService", "service-60s-normal", "service-base" ]
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 4:1-4:63
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 18:1-18:37
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-base-template.conf', lines 8:1-8:31
* type = "Service"
* vars
* influx_append = ""
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-base-template.conf', lines 12:9-12:31
* notification
* interval = 10800
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 25:2-25:32
* period = "businesshours"
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 26:2-26:43
* type = "mail"
% = modified in '/etc/icinga2/zones.d/global-templates/templates/service-60s-templates.conf', lines 24:2-24:32
* nscp_params = "MyService"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 10:3-10:28
* nscp_port = "1248"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 8:3-8:25
* nscp_variable = "SERVICESTATE"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 9:3-9:37
* volatile = false
* zone = "master"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/windowsservices.conf', lines 4:1-4:63
Downtime object:
Object 'cla005!Service MyService!myservice-daily-restarts' of type 'ScheduledDowntime':
% declared in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 195:1-195:57
* __name = "cla005!Service MyService!myservice-daily-restarts"
* author = "icingaadmin"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 196:3-196:24
* child_options = "DowntimeNoChildren"
* comment = "Scheduled downtimes for daily restarts"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 197:3-197:52
* duration = 0
* fixed = true
* host_name = "cla005"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 195:1-195:57
* name = "myservice-daily-restarts"
* package = "_etc"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 195:1-195:57
* ranges
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 199:3-207:3
* friday = "06:45-07:00"
* monday = "06:45-07:00"
* saturday = "06:45-07:00"
* sunday = "06:45-07:00"
* thursday = "06:45-07:00"
* tuesday = "06:45-07:00"
* wednesday = "06:45-07:00"
* service_name = "Service MyService"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 195:1-195:57
* source_location
* first_column = 1
* first_line = 195
* last_column = 57
* last_line = 195
* path = "/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf"
* templates = [ "myservice-daily-restarts" ]
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 195:1-195:57
* type = "ScheduledDowntime"
* vars = null
* zone = "master"
% = modified in '/etc/icinga2/zones.d/global-templates/applyrules/downtimes.conf', lines 195:1-195:57
I guess I will have to try with the debug log enabled and hopefully find something there.