On Samsung devices there's been an outstanding issue of getting the default blue notification led and the only way to override it is to switch the screen on and off again.
Light Flow has done this automatically for notifications that would cause this issue.
I raised the issue with Samsung several months ago and provided them with code and a sample app to show the issue.
They confirmed it being an issue and sent it to HQ for investigation.
Although they don't plan to bring the change to android 6 they have fixed the issue in android 7.
Therefore Light Flow has identified the update to your phone and switched off the setting
->Light Flow->Notification Settings->Device specific and root->Samsung - switch screen on.