Norton system extension blocked

Hi, Norton 360 had some kind of an update and wants to install a system extension. I keep getting the pop-up window that says "System Extension Blocked," that it was signed by Symantec, and that I have to open Security & Privacy System Preferences to approve. It pops up over and over and is really annoying.

However, when I open the preferences, there is no approval button. Occasionally, I'll get a pair of buttons for "MyApplication," both of which say that they were blocked because they're not from an identified developer, with buttons for Open Anyway and Allow. A third button says a profile has been installed that allows additional applications, with a button for Open Profiles. I can trigger these alerts to appear by re-trying the Norton installer, but they disappear too quickly to click on the buttons.

I've contacted Norton support several times, but they haven't been much help. Hoping for some advice here before I just say goodbye to Norton forever.