Troubleshoot this problem by following the steps below:

1. Open the Watch app on your iPhone.

2. Find and select WeChat from the Watch app. If you can't find WeChat, restart your iPhone.

3. After selecting WeChat from the Watch app, disable all options within the menu, wait 10 seconds, and re-enable them again.

4. Open WeChat on your Apple Watch. It may take a few minutes to start for the first time.