Querying UWF through WMI C++ gives wrong values

Question

I'm trying to read UWF status through the WMI provider in my C++ application, but it doesn't seem to give me correct values. (Everything is false/zero.)

When I go through the same interface in PowerShell, it works. Just not sure what I'm doing wrong on the C++ side. HRESULT doesn't give any errors.

C++ code

#include <iostream>

#define _WIN32_DCOM
#include <comdef.h>
#include <wbemidl.h>
#pragma comment(lib, "wbemuuid.lib")

// https://learn.microsoft.com/en-us/windows/win32/wmisdk/example--calling-a-provider-method
// https://learn.microsoft.com/en-us/windows-hardware/customize/enterprise/uwf-wmi-provider-reference

int foo() {
    HRESULT hres;

    // Initialize COM
    hres = CoInitializeEx(0, COINIT_MULTITHREADED);
    if (FAILED(hres)) {
        return 1;
    }

    // Set COM security levels
    hres = CoInitializeSecurity(
        NULL,
        -1,                          // COM negotiates service
        NULL,                        // Authentication services
        NULL,                        // Reserved
        RPC_C_AUTHN_LEVEL_DEFAULT,   // Default authentication 
        RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation
        NULL,                        // Authentication info
        EOAC_NONE,                   // Additional capabilities 
        NULL                         // Reserved
    );
    if (FAILED(hres)) {
        CoUninitialize();
        return 2;
    }

    // Obtain initial locator to WMI
    IWbemLocator* pLoc = nullptr;
    hres = CoCreateInstance(
        CLSID_WbemLocator,
        0,
        CLSCTX_INPROC_SERVER,
        IID_IWbemLocator,
        (LPVOID*)&pLoc
    );
    if (FAILED(hres)) {
        CoUninitialize();
        return 3;
    }

    // Connect to namespace
    IWbemServices* pSvc = nullptr;
    hres = pLoc->ConnectServer(
        _bstr_t(L"root\\standardcimv2\\embedded"),
        NULL,
        NULL,
        0,
        NULL,
        0,
        0,
        &pSvc
    );
    if (FAILED(hres)) {
        pLoc->Release();
        CoUninitialize();
        return 4;
    }

    // Set security levels for the proxy
    hres = CoSetProxyBlanket(
        pSvc,                        // Indicates the proxy to set
        RPC_C_AUTHN_WINNT,           // RPC_C_AUTHN_xxx 
        RPC_C_AUTHZ_NONE,            // RPC_C_AUTHZ_xxx 
        NULL,                        // Server principal name 
        RPC_C_AUTHN_LEVEL_CALL,      // RPC_C_AUTHN_LEVEL_xxx 
        RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
        NULL,                        // client identity
        EOAC_NONE                    // proxy capabilities 
    );
    if (FAILED(hres)) {
        pSvc->Release();
        pLoc->Release();
        CoUninitialize();
        return 5;
    }

    // Get UWF_Filter instance
    BSTR ClassName = SysAllocString(L"UWF_Filter");
    IWbemClassObject* pClass = nullptr;
    hres = pSvc->GetObject(ClassName, 0, NULL, &pClass, NULL);
    if (FAILED(hres)) {
        return 6;
    }

    // Get property values
    // https://learn.microsoft.com/en-us/windows/win32/api/wbemcli/nf-wbemcli-iwbemclassobject-get
    VARIANT TempPropertyVal;
    hres = pClass->Get(_bstr_t(L"CurrentEnabled"), 0, &TempPropertyVal, NULL, 0);
    bool TempCurrentEnabled = TempPropertyVal.boolVal;
    VariantClear(&TempPropertyVal);
    if (FAILED(hres)) {
        return 7;
    }

    hres = pClass->Get(_bstr_t(L"NextEnabled"), 0, &TempPropertyVal, NULL, 0);
    bool TempNextEnabled = TempPropertyVal.boolVal;
    VariantClear(&TempPropertyVal);
    if (FAILED(hres)) {
        return 8;
    }

    std::cout << "current session is " << (TempCurrentEnabled ? "enabled" : "disabled") << "\n";
    std::cout << "next    session is " << (TempNextEnabled ? "enabled" : "disabled") << "\n";

    pClass->Release();
    pClass = nullptr;
    SysFreeString(ClassName);

    // Get UWF_Filter instance
    ClassName = SysAllocString(L"UWF_Overlay");
    hres = pSvc->GetObject(ClassName, 0, NULL, &pClass, NULL);
    if (FAILED(hres)) {
        return 9;
    }

    // Get property values
    hres = pClass->Get(_bstr_t(L"AvailableSpace"), 0, &TempPropertyVal, NULL, 0);
    long TempAvailableSpace = TempPropertyVal.lVal;
    VariantClear(&TempPropertyVal);
    if (FAILED(hres)) {
        return 10;
    }

    hres = pClass->Get(_bstr_t(L"OverlayConsumption"), 0, &TempPropertyVal, NULL, 0);
    long TempOverlayConsumption = TempPropertyVal.lVal;
    VariantClear(&TempPropertyVal);
    if (FAILED(hres)) {
        return 11;
    }

    hres = pClass->Get(_bstr_t(L"WarningOverlayThreshold"), 0, &TempPropertyVal, NULL, 0);
    long TempWarningOverlayThreshold = TempPropertyVal.lVal;
    VariantClear(&TempPropertyVal);
    if (FAILED(hres)) {
        return 12;
    }

    std::cout << "current available space: " << TempAvailableSpace << "\n";
    std::cout << "current overlay consumption: " << TempOverlayConsumption << "\n";
    std::cout << "current warning threshold: " << TempWarningOverlayThreshold << "\n";

    pClass->Release();
    pSvc->Release();
    pLoc->Release();
    CoUninitialize();
    SysFreeString(ClassName);
    return 0;
}

int main()
{
    std::cout << foo();
    std::cout << "\n";
    return 0;
}

Output

current session is disabled
next    session is disabled
current available space: 0
current overlay consumption: 0
current warning threshold: 0
0

PowerShell code

Get-WmiObject -namespace "root\standardcimv2\embedded" -class UWF_Filter;
Get-WmiObject -namespace "root\standardcimv2\embedded" -class UWF_Overlay;

Output

__GENUS          : 2
__CLASS          : UWF_Filter
__SUPERCLASS     :
__DYNASTY        : UWF_Filter
__RELPATH        : UWF_Filter.Id="UWF_Filter"
__PROPERTY_COUNT : 5
__DERIVATION     : {}
__SERVER         : localhost
__NAMESPACE      : root\standardcimv2\embedded
__PATH           : \\localhost\root\standardcimv2\embedded:UWF_Filter.Id="UWF_Filter"
CurrentEnabled   : True
HORMEnabled      : False
Id               : UWF_Filter
NextEnabled      : True
ShutdownPending  : False
PSComputerName   : localhost

__GENUS                  : 2
__CLASS                  : UWF_Overlay
__SUPERCLASS             :
__DYNASTY                : UWF_Overlay
__RELPATH                : UWF_Overlay.Id="UWF_Overlay"
__PROPERTY_COUNT         : 5
__DERIVATION             : {}
__SERVER                 : localhost
__NAMESPACE              : root\standardcimv2\embedded
__PATH                   : \\localhost\root\standardcimv2\embedded:UWF_Overlay.Id="UWF_Overlay"
AvailableSpace           : 917
CriticalOverlayThreshold : 2040
Id                       : UWF_Overlay
OverlayConsumption       : 2155
WarningOverlayThreshold  : 2032
PSComputerName           : localhost