When I hit Save after changing Shipping – says Unauthorized

I have installed the plugin to WorPress correctly, added all the relevant options, installed the Chrome Plugin and now when I amend the shipping type and click save I am greeted with an Unauthorized message.

I also tried the suggestion in another post to add
RewriteEngine On
RewriteCond %{HTTP:Authorization} ^(.*)
RewriteRule .* – [e=HTTP_AUTHORIZATION:%1]

To my .htaccess file, but that did not work either.