Why Webview2 set value of an input element but value desapears after submiting the form as never had been set?

I’m calling ExecuteScriptAsync and pass a script that find an input element and set its value. After I submit the form, the site behaves like there isn’t any text in the input. Clicking in the submit button, the text desapears. Clicking into the input element, same occurs. See the code below.

await webView.CoreWebView2.ExecuteScriptAsync("var obj = document.evaluate("//descendant::input[@placeholder='Type the code']", document,  null,  XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue; if (obj != undefined && obj != null) {obj.value='AP37060';}");

The text is changed, but it seems as nothing is there. Can somebody help me? Thanks.