This occurs when there is some coruption of the data bases between Comcast and Norton. Sometimes the remove and reinstall of Norton corrects the problem - other times not. The only sure fix is to
follow the link below.
Once you contact chat and they tidy up the data bases - things should work fine.
The link provided no longer works???
I have had the same thing happen to me countless times. It requires a uninstall and reboot and then a download and install. Xfinity \ Comcast support is useless. I will usually be directed to call norton support who will then direct me back to xfinity. I am finally surrendering due to time and money and just going to purchase my own copy. Which is what xfinity and Norton want! Congrats ou now have a disgruntled customer! Both palces still making money
Have you tired the new Norton offering from Comcast?
Please give it a try before spending more money on the retail version of Norton.