Do you receive notifications from other apps?
Note sure if it’s exactly the same on a Note 8, you might have to check your user manual, but go to your phone settings, Lock Screen settings, click on Notifications (these are lock screen notifications, not the regular notification settings), make sure they are turned on, make sure Hide Content isn’t checked, make sure Notifications to Show is set to Alert and Silent (or at least whichever you have your Blink and other important notifications set to), Always On Display settings will let you always display notifications even when you aren’t using your phone or tap to show them for ten seconds. I have App Icon Badges in my Notification settings turned on so if I don’t hear the notification, I see the notification badge at top of my phone the next time I pick it up.
If you go into the Ringtone settings, there is a separate volume setting for Notifications that might be turned off. Strange place for it, but that’s where it is on mine.
If you have Data Saver turned on, some apps may not use data in the background and you won’t get notifications until you’re back on wifi. That’s a choice you’ll have to make.
As much as we hate to do it, phones are so complicated these days that it really does pay off to spend some time with the user manual. I upgraded from a Samsung to a Samsung and absolutely everything changed.