I was able to get this to work. Instead of using my own sendBack function, i used the postMessage and WebMessageReceived.

JS code:

wWebView.CoreWebView2.ExecuteScriptAsync("window.addEventListener('message', function (event) {if (event.data && event.data.type === 'CPResponse') {window.chrome.webview.postMessage(JSON.stringify(event.data.data));}}, false);")

VB code:

Private Sub wWebView_WebMessageReceived(sender As Object, e As CoreWebView2WebMessageReceivedEventArgs) Handles wWebView.WebMessageReceived
        sendBack(e.TryGetWebMessageAsString())
    End Sub