Unable to Load Web Settings in WPF application when readAccessProperties/writeAccessProperties contain group property references

Am using ASP.NET AJAX Profile service from a WPF UI. Using the Project Settings designer in the UI project, I am attempting to load settings into the designer from the Profile service using the Load Web Settings function for an authenticated user. For all basic (non-grouped) properties works great. As soon as I add any group property references in the readAccessProperties/writeAccessProperties attributes, get the following error:

Value does not fall within expected range

Expect the settings designer does not support group property references, but hoping somebody can confirm.

Here's my profile service setup:
<profile defaultProvider="MyProfileProvider">
<providers>
...
</providers>
&l ...