Notifications not working [Android]

Hi all,
I've had my 5X for around a year now and sms/email/s-media notifications worked perfectly until around a month ago.
I have the latest version of Connect on my Android phone and my 5X is on software version 8.
I've done the usual checks to make sure it's not just gremlins in the system (resets, turning notifications on and off again etc).
I've also searched the forum for and info, but to no avail.
I would greatly appreciate you r thoughts/advice on the issue as I'd love to get them working again.
Many thanks in advance.