Android Wear 2.0 has been a mixed bag, to say the least. The platform's largest update yet hasn't been popular with everyone, and several notable bugs plus a slow rollout have hindered its success. Another widely-reported bug related to setting up Google accounts on AW 2.0 still hasn't been fixed, almost three months after it was first reported.
When you set up an Android Wear 2.0 watch, you are prompted to copy a Google account from your phone to the watch. This is used for the Google Play Store, as well as other apps that sync with your account. Unfortunately, this step just plain won't work for many users, leaving their watches gimped on functionality.
The official thread for the issue on the Android Wear Help Forum is almost up to 300 replies. There have been a few workarounds posted by users, such as disabling two-factor authentication on your Google account or switching the watch to Wi-Fi, but it really should just work by now.
One Google Community Manager said the company is "working on a fix," but didn't offer any ETA. At this rate, Samsung's Tizen-based smartwatches are looking better every day.