I'm using a Samsung S6 Edge plus that is running Marshmallow. Notifications are turned on and for everything else they work fine. For Kik, an Internet message system, they don't. Before downloading Marshmallow notification worked fine, but now I have to open Kik to see if I have any messages,when they download. Kik settings are also set to receive notifications. The only other variable is that I'm wearing a Gear 2 which is connected to the Edge by Bluetooth.