Sharepoint - 2013 Results Source query path shows zero relevantresults

I found the cause of my issue. This may not explain why Path works for some, but this route allowed me to properly filter my results:

The Path managed property is configured as Complete Matching, meaning that my Path values of /uk or http://mysite.net/uk were doomed to failure, as they are not complete URLs.

My solution was to create a new managed property (which I called PagePath) using the same "Mapping" values as Path, but not checking the Complete Matching box.

Now, in my query, I can use PagePath:/uk and I only see results from the /uk site and above.

Hope this helps someone :)