The smart lock on my S9+ was not workng correctly either. I entered the actual address and the circle around it on the map was correct, but the feature would not work. I edited the address using latitiude/longitude coordinates and had the same problem. Finally, I eliminated both addresses shown and used only a GPS signal (by tapping on the map shown for my current location). Once entered, i restarted the phone and the smart lock finally worked.
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