Recently, I migrated a site from the flywheel to WP Engine using Migrate Guru plugin.
After migration, I was asked to add browser authentication when I try to access the homepage. It was not asking the authentication when I try to access wp-admin.
Below is the screenshot what I was getting.
So I connected WP Engine’s support guy. And in my case there was a third party plugin was creating the issue. After deactivating that plugin, issue was fixed.