Huawei WATCH 2 Faq page 7

 You cannot make calls on your watch when your watch and phone are connected
over Wi-Fi. To make calls, use Bluetooth to connect your and phone
 If the issue persists, try restarting your watch.
10:Why does my watch not respond when I issue the "OK Google" voice
command?
If your watch doesn't respond to voice commands, follow the steps below:
 Confirm that your watch is connected to your phone over Bluetooth.
 Ensure that your watch is not downloading large amounts of data, such as an OTA
update package.
 Confirm that you can send voice messages to your contacts using
WeChat/WhatsApp/Facebook messenger.
 Try saying "OK Google" again when your watch's screen is on.
 Switch your phone's Internet connection to Wi-Fi or mobile data and then try again.