I am getting phantom or mystery notifications on my Samsung Galaxy S7. Every day at around the same time (10:00 - 10:05 AM), and throughout the day randomly (3-4 different times). I hear a notification sound, but have nothing in my notification area. I hear it even with "Do Not Disturb" turned on. Looking at my notification history, it first appeared that Weather Underground was causing the notification, so I uninstalled it and replaced it with AccuWeather. I had the same problem, and it appeared to be AccuWeather, so I uninstalled it. Now that I don't have a weather app, the most recent notification that matches up with that time came from "System UI" with the body "Select Keyboard". Yesterday, it was "System UI" again, but this time "Do Not Disturb turned on". I did not turn DnD on or off at that time, and even when I do, I do not receive a notification sound. I don't know if it might be related, but there are also several "Select Keyboard" notifications in a row.