Sprout Email PHP Warning Trying out Sprout Email on a fresh local (MAMP/PHP 7.1) install, and whenever I try and create a new Notification I get

PHP Warning – yii\base\ErrorException
get_class() expects parameter 1 to be object, string given


in /vendor/barrelstrength/sprout-base-email/src/controllers/NotificationsController.php

Tried a few different PHP versions in case that helps, but same. Anyone experienced this before and got any suggestions? Much appreciated.
Thanks Ben. Thought I had very latest version of the plugin, but just updated both Craft and plugin, and problem solved!