Customiser Broken after Updating Permalinks

Hi there,

I have a brand new install of WordPress and have enabled MultiSite.
Upon creating a boilerplate theme to work on I encounter a problem when trying to change the permalinks to just the name.

The customiser breaks and I receive this error message within the browser:
Localhost redirected you too many times.

This problem isn’t just local to the theme, its for all of them, very strange indeed.

I am using XAMPP and phpmyadmin, any help greatly appreciated!

Thanks.