I'm also having issues with the magazine quizzes. I've tried to access multiple quizzes, even going back to previous years, and I just get "Content loading..." on the page.
When I go into developer tools, I do notice this error:
Failed to load resource: net::ERR_NAME_NOT_RESOLVED
So, it might be that a third-party provider is having an issue.
Looks like InfoSecurity Professional magazine quizzes that are prior to July/August 2022 Issue are no longer available.