This is exactly my experience also, and no help from Utec has fixed the problem. It was the only reason why I purchased this lock and in less than 2 years this key feature does not work!
Have you been able to fix your lock yet?
Under Australian consumer law, products need to be fit for purpose. Even though there is an 18 month warranty on electronics there is an expectation that a lock should last more than 18 months. They cannot manufacture a lock an it stop working after 18 months. Has anyone even got a lock where the finger print reader lasts more than 18 months?