I am having problems with Smart Scan as well https://community.norton.com/t/smart-scan-results-only-shows-you-what-is-slowing-down-computer-and-an-advertisement-to-try-norton-ultimate-utilities/528023 but not in the way you are having so I took that off the schedule runs and I only use Quick Scan now. This latest update to Norton seems to be really buggy.
Respectfully