Converting CString to UTF-8 with CT2CA is corrupting some characters

I am trying to write this value to a UTF-8 XML encoded text file:

Estudante - Leitura da Bíblia

I am using a lambda function:

auto AddLabel = [](tinyxml2::XMLDocument& rDoc, tinyxml2::XMLElement* pLabels, LPCSTR szElement, CString strValue, int iIndex = -1)
{
    tinyxml2::XMLElement* pLabel = rDoc.NewElement(szElement);
    if (pLabels != nullptr && pLabel != nullptr)
    {
        pLabel->SetText(CT2CA(strValue));
        if (iIndex != -1)
        {
            pLabel->SetAttribute("Index", iIndex);
        }
        pLabels->InsertEndChild(pLabel);
    }
};

But I end up with a corrupt character when I open the XML in Notepad++:

This is how I save my XML file:

bool CMeetingScheduleAssistantApp::SaveToXML(CString strFileXML, tinyxml2::XMLDocument& rDocXML)
{
    FILE    *fStream = nullptr;
    CString strError, strErrorCode;
    bool    bDisplayError = false;
    int     iErrorNo = -1;

    using namespace tinyxml2;

    // Does the file already exist?
    if (PathFileExists(strFileXML))
    {
        // It does, so try to delete it
        if (!::DeleteFile(strFileXML))
        {
            // Unable to delete!
            AfxMessageBox(theApp.GetLastErrorAsString(), MB_OK | MB_ICONINFORMATION);
            return false;
        }
    }

    // Now try to create a FILE buffer (allows UNICODE filenames)
    const auto eResult = _tfopen_s(&fStream, strFileXML, _T("w"));
    if (eResult != 0 || fStream == nullptr) // Error
    {
        bDisplayError = true;
        _tcserror_s(strErrorCode.GetBufferSetLength(_MAX_PATH), _MAX_PATH, errno);
        strErrorCode.ReleaseBuffer();
    }
    else // Success
    {
        // Now try to save the XML file
        const XMLError eXML = rDocXML.SaveFile(fStream);
        const int fileCloseResult = fclose(fStream);
        if (eXML != XMLError::XML_SUCCESS)
        {
            // Error saving
            bDisplayError = true;
            strErrorCode = rDocXML.ErrorName();
            iErrorNo = rDocXML.ErrorLineNum();
        }

        if (!bDisplayError)
        {
            if (fileCloseResult != 0)
            {
                // There was a problem closing the stream. We should tell the user
                bDisplayError = true;
                _tcserror_s(strErrorCode.GetBufferSetLength(_MAX_PATH), _MAX_PATH, errno);
                strErrorCode.ReleaseBuffer();
            }
        }
    }

    if (bDisplayError)
    {
        if (iErrorNo == -1)
            iErrorNo = errno;

        strError.Format(IDS_TPL_ERROR_SAVE_XML, strFileXML, strErrorCode, iErrorNo);
        AfxMessageBox(strError, MB_OK | MB_ICONINFORMATION);

        return false;
    }

    return true;
}

Why is this happening? I can confirm that strValue has the correct content as a CString. I can confirm this:

if (strValue.Left(7) == L"Leitura")
{
    AfxMessageBox(strValue);
    pLabel->SetText(CT2CA(strValue));
    AfxMessageBox(CA2CT(pLabel->GetText(), CP_UTF8));
}

When I do the CA2CT call the result has the corrupt í character. So How can I get around this problem? tinyxml2 expects a UTS-8 enconded string:

void    XMLElement::SetText( const char* inText )
{
    if ( FirstChild() && FirstChild()->ToText() )
        FirstChild()->SetValue( inText );
    else {
        XMLText*    theText = GetDocument()->NewText( inText );
        InsertFirstChild( theText );
    }
}

I have the same issue for a variety of characters in strings depending on the language. Another affected language is Polish.

How do I write my string without corrupting it as UTF8?

The error was simple:

auto AddLabel = [](tinyxml2::XMLDocument& rDoc, tinyxml2::XMLElement* pLabels, LPCSTR szElement, CString strValue, int iIndex = -1)
{
    tinyxml2::XMLElement* pLabel = rDoc.NewElement(szElement);
    if (pLabels != nullptr && pLabel != nullptr)
    {
        pLabel->SetText(CT2CA(strValue, CP_UTF8));
        if (iIndex != -1)
        {
            pLabel->SetAttribute("Index", iIndex);
        }
        pLabels->InsertEndChild(pLabel);
    }
};

I was missing the CP_UTF8 parameter to the CT2CA macro.