Hi
The following steps may help (check after each):
If you have not yet done so, update your iPhone and Apple Watch to the latest software, starting with your iPhone:
Check your settings:
- On your iPhone, in the Watch app, go to: My Watch (tab) > General > Wake Screen > check that Wake Screen on Wrist Raise is turned on.
Check that Theatre Mode is not enabled on your Apple Watch:
You might also wish to use the following settings:
- On your iPhone, in the Watch app, go to: My Watch (tab) > General > Wrist Detection - turn this on.
- On your iPhone, in the Watch app, go to: My Watch > Passcode > Turn Passcode on.
- Also on the Passcode settings screen, enable Unlock with iPhone.
- With these settings, after putting it on your wrist, your watch will then unlock after whatever you do first: either unlocking your watch manually (by entering the passcode) or unlocking your iPhone.
- It will then remain unlocked (including when the screen is asleep) until you remove it from your wrist. When you remove your watch, it will lock automatically.
Restart both your iPhone and your Apple Watch, turning both off together, then restarting your iPhone first:
Unpair and re-pair your watch:
If the issue then 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, including - if recommended - to arrange for your Apple Watch to be checked and, if required, serviced:
Apple Watch Service Answer Center - Apple Support