Unable to set custom header in CoreWebView2WebResourceRequest for NavigateWithWebResourceRequest

I am trying to set custom header to WebResourceRequest before navigating using NavigateWithWebResourceRequest API. I am using CoreWebView2WebResourceRequest API to create WebResourceRequest.

Somehow custom header is always ignored in normal execution. If I put break-point or sleep (~100 millisecond), the custom header is set properly (and visible in Inspect -> Network window). I am using WebView2 SDK version 1.0.1245.22.

Tried below work-arounds:

1. Using first dummy header as mentioned in issue #1123.
2. Setting headers using ICoreWebView2HttpRequestHeaders interface as suggested in MS_docs

Below is code snipped example I am using

	wrl::ComPtr<ICoreWebView2WebResourceRequest> webResourceRequest;
	wrl::ComPtr<ICoreWebView2HttpRequestHeaders> requestHeaders;

	hr = webviewEnvironment2->CreateWebResourceRequest(
		url.c_str(),
		L"GET",
		nullptr,
		L"",  // Tried setting headers as L"My-Header: 1" or L"Dummy-Header: 1\r\nMy-Header: 1\r\n"
		&webResourceRequest);

	if (hr.Failed())
	{
		return false;
	}

	// 
	hr = webResourceRequest->get_Headers(&requestHeaders);
	if (hr.Succeeded() && requestHeaders)
	{
		for (const auto& header : httpHeaders)
		{
			requestHeaders->SetHeader(header.first.c_str(), header.second.c_str());
		}
	}

	// wait for 100 milliseconds to ensure correct setting of custom headers
	std::this_thread::sleep_for(std::chrono::milliseconds(100));

	wrl::ComPtr<ICoreWebView2_2> webView2;
	hr = m_webView.As(&webView2);

	if (hr.Failed() || !webView2)
	{
		return false;
	}

	hr = webView2->NavigateWithWebResourceRequest(webResourceRequest.Get());

Start with the issue's CreateWebResourceRequest, get_Headers, SetHeader, and NavigateWithWebResourceRequest calls, using WebView2 SDK 1.0.1245.22. Reproduce the request with and without the 100 ms delay and inspect the custom header in the Network window. Done means the custom header is reliably included without a breakpoint or sleep.