Firefox was blocking a redirect when I clicked on an OFAC email to their legitimate website. Searching, I came up with this article, and WANT TO OFFER A TIP for other readers: https://support.mozilla.org/bm/questions/1253651
If you are getting a blank page or annoying prompts to Allow a redirect, here's how you can turn the redirect block off: (1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk. (2) In the search box above the list, type or paste access and pause while the list is filtered (3) If the accessibility.blockautorefresh preference is bolded and "modified" or "user set" to true, double-click it to restore the default value of false
The page threw an error that it was blocked - no offer to allow it. The referenced setting was already turned off (false) in my browser, so I toggled it OFF AND BACK ON.