Membership restriction incorrectly protecting pages with no records

Membership is great and appears to work perfectly.

I'm using it to restrict access to sections of woocommerce. As i don't have woocommerce categories to choose from I am using URL Groups.

However, I'm finding that pages that normally return 'no results' like http://projectclothing.com.au/events/ gets the protected page. If there are events to show, then it works fine.

Another example, the posts archive:
http://projectclothing.com.au/2014/04/ this page has results and works fine. However if you try http://projectclothing.com.au/2014/05/ - a month archive with no records, you see the protected page again.