Welcome to the Forums @JamieDavid.
This might be happening because the J4 is not part of the supported devices list. This means that the app has not been fully optimized to work with that phone.
As long as it fulfills the minimum requirements, Android 4.4 and Bluetooth 4.0, there is a possibility that it can work but we cannot guarantee it. Some users of unsupported devices have mentioned that following these steps helps for the notifications.
Let me know if you have any further questions.
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