Zillow -> GetUpdatedPropertyDetails - Error 501: Protected data is unavailable through API

Question

I have problem with Zillow API. GetDeepSearchResults and GetDeepComps return results properly, but GetUpdatedPropertyDetails returns an error 501.

Here is documentation:

GetUpdatedPropertyDetails documentation

I don't exceed any call limits or so. Querying any random property found on the website results in the same error.

Here is an example request:

http://www.zillow.com/webservice/GetUpdatedPropertyDetails.htm?zws-id=X1-ZWz1d5yidvvpcb_94p25&zpid=45732368

API key (zws-id) in above link was publicly available, so you can test with it for science, my private key generates the same result.

Is there any way to get proper response?