According to Google Support, Autocomplete (NEW) Requires BOTH: Places (New) API + Places Legacy to be enabled (who knows why?) -- I was instructed to enable Legacy by going to: https://console.cloud.google.com/apis/library/places-backend.googleapis.com
Once that is enabled, the Autocomplete element worked as expected when using their Sample code: https://developers.google.com/maps/documentation/javascript/examples/place-autocomplete-element