Logging in issue with password added programmatically using JavaScript

Question

I have a javascript where i get the password exposed via an api. I am appending this password to the password field, i can the see the password being masked and also password is correct. but the i am not able to login. if i manually enter the password manually and try logging in, it will work. Not sure whats the issue.

function getElementByXpath(path)
{
    return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}

function main()
{
  const baseUrl = "API to get passowrd";
  const id= '1234';
  const params = new URLSearchParams({ id: id});
  const url = `${baseUrl}?${params.toString()}`;
  let password = "";
    token = 'getting from another endpoint'

   fetch(url, {
    method: 'GET',
    headers: {
      'Authorization': `Bearer ${token}`,
      'Accept': `*/*`,
      'Content-Type': `application/json`
    }
  }).then(response => response.json())
    .then(data => {
      password = data.password;
      //console.log(data);
      var passwordXpath = 'xpath of password field';
      var passwordField = getElementByXpath(passwordXpath);
      passwordField.type = 'hidden';
      passwordField.value = password
      //getElementByXpath(passwordXpath).value = password;
    })
  .catch(error =>{console.error(error);});
}
main();

this is the code. It works for most of the websites. for few of them i am facing this issue. Please help if anyone has a solution