In Android 6.x (“Marshmallow”) and above, a new permission has been added that must be granted to SIFAM in order for the Overlay to work. When enabling the Overlay in Settings, SIFAM should have told you about it and given you instructions on how to enable it. However it is possible that the setting might have gotten reset somehow. If you are having problems with the overlay, you should check to make sure that it is enabled. Here are instructions on how to do this.
