Do all the relevant permissions and settings in your apps and in the phone's settings look to be right ?
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
I've have the same problem. Don't think there's any solution. Samsung won't help.
@Daimytron: Can you try pressing and holding the Volume Down and Power buttons together for around 10 seconds until the phone vibrates, and restarts. Don't worry, this won't affect your personal data or settings. Following the restart, head to Settings > Lock screen > Notifications > On > Set your preferences e.g. Icon only/Details, Hide content on/off etc > Show on Always On Display > On. If the problem relates to your Always On Display, then tap the Back button to return to the Lock Screen settings > Always On Display, and select 'Show for new notifications'.
If the issue persists, head to Settings > Apps > Select an app that you're currently not getting notifications from when the phone is idle, and check the Lock screen notification settings from here.