New Post: SSO deploy seems to succeed, what causes the error "The mapping does not exist"?

We have set this up like this:
In the first ItemGroup:

<IncludeSSO>True</IncludeSSO>

This in it's own item group:

<ItemGroup>
    <PropsFromEnvSettings Include="SsoAppUserGroup;SsoAppAdminGroup" />
  </ItemGroup>

Where these settings are set for each environemnt in the environment file.

This is all that should be needed.
If we use the "Edit SSO Settings" link in the installed application's start menu folder, it shows all settings we specified in the environment's file.