QRZ fills in all the correct information (contacts name, address, etc.) except for the grid square. It lists everyone as being at DN11.
Sounds like a Log4OM configuration issue, rather than a QRZ issue. Perhaps file a request in the Log4OM forum page or in the Logging Software forums here on QRZ.
The XML interface function for non-subscribers is very limited. It's essentially intended for basic functional testing for users to evaluate if they want to upgrade to a subscription. I'm not sure off the top of my head what the limits on the returned data is, but it's very likely that it's just not providing location as part of the limited data it returns. 73, Steve KF8KI