Both the extension and the receiving application are in the same app group. I can't find the issue. It doesn't seem to be a problem with entitlements. Maybe an issue with the string formatting/conversion? Maybe I am not allowed to send distributed center notifications from the camera extension? I am sending the notification calling: func notifyChangeInUsage() { os_log("Notifying the virtual camera change in usage", log: cdsLog, type: .info) // this is logged DistributedNotificationCenter.default().postNotificationName(NSNotification.Name("VirtualCamUsageChanged"), object: nil, userInfo: nil, deliverImmediately: true) } And receiving it in the other end, subscribing with std::string notification = "VirtualCamUsageChanged" [mObserverClassInstance subscribe:@(notification.c_str())]; where subscribe is the following method, which is tested to be working. - (void)subscribe:(NSString *)notification { [[NSDistributedNotificationCenter defaultCenter] addObserver:self selector:@selector(callCallback:) name:notification object:nil suspensionBehavior:NSNotificationSuspensionBehaviorDeliverImmediately]; }