If your Apple Watch is not delivering notification alerts as expected, the following steps may help:
On your iPhone in the Watch app, go to: My Watch > General > Wrist Detection - turn this on.
- Note that Wrist Detection can be affected by temporary or permanent skin changes, such as by some wrist tattoos.
If Passcode is enabled, check that you are unlocking your watch each day after placing it on your wrist and that you are wearing your watch sufficiently snugly (your watch may otherwise believe that it has been removed from your wrist).
In respect of Messages:
- On your iPhone, in the Watch app, go to: My Watch > Messages:
- Perhaps choose Custom and check - under Alerts - that Show Alerts, Sound and Haptic are each enabled.
Check that Theatre Mode is not enabled on your Apple Watch:
- When viewing the time on your watch, swipe up to open Control Centre.
- Tap the Theatre Mode button to toggle the setting on / off.
- https://help.apple.com/watch/#/apddfca28d21
Check that Do Not Disturb mode is not enabled on your watch:
- When viewing the time on your watch, swipe up to open Control Centre.
- Tap the Do Not Disturb button (crescent moon icon) to toggle the setting on / off.
On your iPhone, in the Watch app, go to: My Watch > Sounds & Haptics:
- Check that the Alert Volume is towards the centre or right hand side;
- Check that Silent Mode is not enabled;
- Check that Haptic Strength is set to the middle or far right hand side of the slider.
Confirm directly on your Apple Watch that Silent Mode is not enabled:
- When viewing the time on your watch: swipe up on the screen to open Control Centre > check whether Silent Mode (button with a crossed out bell icon) is enabled.
If the issue persists, the following further steps may help:
If you have not yet done so, update your iPhone and Apple Watch to the latest software, starting with your iPhone:
- Update the iOS software on your iPhone, iPad, or iPod touch - Apple Support
- Update the software on your Apple Watch - Apple Support
Close the Watch app and restart both your iPhone and your Apple Watch:
- On your iPhone: double-click the Home button, then swipe up on the Watch app preview.
- Turn both devices off together, then restart your iPhone first:
Unpair and re-pair your watch:
- The Watch app on your iPhone takes a backup of your watch automatically when unpairing via the app. Choose to Restore from Backup during set up. Most data and settings will be restored, with some exceptions (eg Apple Pay cards, passcode).
- Unpair your Apple Watch and iPhone - Apple Support
- Set up your Apple Watch - Apple Support
If the issue then still persists, I suggest that you contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider for assistance: