Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
The best way to proceed here, is to first go to your settings, bluetooth, and unpair or forget the Vivosmart.
Then, turn the vivo smart off.. And then go back to garmin connect.
Inside garmin connect,
Open the Garmin Connect Mobile app.2. Tap on the Menu icon (three lines) located in the upper-left corner.3. Tap on 'Devices'.4. Tap on the 'Info' icon (circled "i") located in the upper-right corner.5. Tap on 'Remove a Device'.6. Select the device you would like to remove.7. Tap on 'Forget Device'.
Once forgotten, Now turn on the Vivoactive and garmin connect should see it and allow you to pair with it. Let me know if you get stuck or run into any issues.
I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.