Sesnors with sensor_ignore=1 sometimes not gray'ed

Today I wrote a small workaround to ignore alerts from shutdown ports to avoid false positive alarms.

UPDATE sensors,devices,ports SET sensors.sensor_ignore='1' WHERE ports.ifAdminStatus = 'down' AND devices.device_id = ports.device_id AND ports.device_id = sensors.device_id AND ports.port_id = sensors.measured_entity

But in the webinterface I see that some sensors are still colored and not "gray'ed". See attached screenshot for example. Some sensors of the ports are gray, some not. In SQL Database the affected sensors are configured with "sensor_ignore=1".