Apple Watch doesn't show messages in Messages app

Do this on the iphone and test again.

Settings, Messages, Turn off iMessage 

Settings, Face Time, Turn off Face Time 

Restart the phone. 

Settings, Messages, Turn on iMessage, SMS, MMS 

Settings, Messages, send & Receive, "Start new conversations from", select your Apple ID which should now be there. 

Settings, Messages, send & Receive, "You can receive imessages to and reply from",  ensure your phone/watch number is selected.

Settings, Face Time, Turn on Face Time 

Also check there is no red phone symbol at top of Watch face

Hello!

I had this issue since I got my apple watch 8. I tried everything - turn off iMessages / changing iCloud settings / restarting both devices / updating all devices etc etc, but the only thing that helped me is to unpair and pair them back to my iPhone (with restoring from a backup).

Now I can finally see both SMS and iMessages on my Apple Watch - Messages app :)

Hope that helps!

There would not be notifications if, for example, the iphone was open, but are you saying if you open messages app on Watch the SMS are not there at all?

They already tried that (a year ago BTW)