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Try go to settings-apps-all-media storage and reset defaults.
Clear data,see how it goes.
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Restart the phone,when you remove the seals,nothing appears?
What ringtone did you have?go to settings-ringtone-tap a little note
I know,restart is required after clearing data for media storage,my guess was that it is an app causing the notification to appear.
LE: Do you have an app called water or waterproof or something like that in your settings-apps-all?