There are several common reasons why notifications from messages may not be coming through:

• Focus mode or Do Not Disturb mode is enabled, which can block notifications. Checking and disabling these modes often resolves the issue.
• Specific contacts or threads may be set to "Hide Alerts" or muted, preventing notifications from those contacts.
• Notification settings for the Messages app may be turned off or misconfigured, so ensuring notifications are allowed, banners and sounds are enabled, and the lock screen shows alerts is important.
• Sometimes restarting the device or toggling message notifications off and back on can fix notification glitches.
• On some devices, message forwarding or background app restrictions can interfere with notifications.

For iPhones, specifically:

• Check under Settings > Focus to ensure no mode is on.
• In Messages, check pinned contacts or individual chat settings to see if "Hide Alerts" is enabled and disable it.
• Verify Settings > Notifications > Messages allows alerts, sounds, banners, and lock screen notifications.
• Restart the phone, toggle airplane mode, or turn iMessage off and on if needed.

For Android phones:

• Ensure app notifications are enabled for the Messages app in system settings.
• Check that contacts are not muted or blocked.
• Disable Do Not Disturb mode and any power saving settings that limit background activity.

Trying these steps should help restore message notifications.