This is a problem in very specific circumstances, and it is only fixed by adding an exception to the Web Shield. But why?
When I try to login to certain sites built with WordPress, using the current Safari browser on the current macOS Catalina, I get a message from Safari saying it can't open the page. The very same login works in Chrome on the very same system on the very same site. The only way to get around the problem when using Safari is to add the site as an exception to the Web Shield.
This behaviour does not happen on all sites built with WordPress (these are sites I have built which I'm trying to log in to). Only some. But I also use a local server called 'Local by Flywheel'. The problem occurs on all my local sites. I can't log in to them on Safari without a Web Shield exception. But I can log in to them on Chrome with no problem and no exception.
Can you help? Is there some setting in Safari on the Mac triggering the Web Shield to block the traffic? What is it?