SOLUTION FOR SAMSUNG GALAXY WATCH 4 OWNERS! 1. Uninstall the Google Pay app from your watch 2. Restart your watch 3. Reinstall the Google Pay app on your watch 4. Restart your watch (don't skip this step!) You should be able to add credit cards to your watch now. I have not tried making payments with the watch yet but hopefully it will work. Please help to upvote this solution. Zero thanks to the person replying useless advice to the numerous feedback and adding to our frustrations.