How to add to trusted devices on smart lock?

Same here wont work on my pixel xl , the 645 music i had worked fine on the pixel xl and pixel 2 on trusted devices.

Did you pair both to the Connect app and also to the phone itself? Are all the permissions on your phones allowing smart unlock for Garmin?

Paired through connect, you cant pair it to the phone through the phone, it says already paired.

I tried first removing the phone from Garmin connect, and then pairing it with the phone itself. After I did this I tried adding it to Garmin Connect, but wasnt able to put it into pairing mode as the watch was already paired.

If the Connect app shows the VA as being paired, long press it in the app and choose update the connection. If it's not paired in the app but it is on the phone, unpair it from the phone, pair to the app, and then long press to update the connection.

If that's not it, then check your permissions for the Connect app.

Since nobody else is commenting on smart lock but Garmin Connect, here is what you do on the pixel 3 (on Android Pie 9)

Go to settings, then security & location. You should see smart lock there under device security. You should then be able to add it under trusted devices. 

Works on my fenix 3hr ! I had almost given up on this feature.  Thank you

Just had problem. I reset my Pixel (1) and it paired Vivoactive 3 through GC, but then wasn't listed in BT settings or in Smart Lock add Trusted Devices. I fixed this by holding the side button, then tapping the green phone icon in the lower right of the VA3. Then I tapped it again. Then it appeared as an available device to pair to my Pixel. This was with Android 9. Don't remember if Android 10 had the same issue. Sidenote Android 10 kills smartcase on/off functionality (for now).