How the Bypass Url Works
The bypass url allows you to create a url that you can give to someone to bypass the coming soon page.
By default starting in Version 4 the bypass url uses a generic user with no privileges to access the site. This method is used to because heavily cached host like WPEngine or caching plugin do not cache content for logged in users. So when they use the bypass url they are logged in as that user.
This does not work for some use cases. We have an alternate method that does not use a user but also does not worked on heavily cached sites.
You can use a cookie only method that was used in Version 3 by adding:
in the Plugin API field under the advanced tab.