Refused to display 'https://www.accountkit.com/...' in a frame because it set 'X-Frame-Options' to 'deny'

I'm getting this error when I try to load the modal from Account Kit.

I'm using the same solution implemented in a previous code that I did. So it is weird that it's not working.

It's not working in develpment either in production (heroku).

even tried the next code, but didn't work.

config.action_dispatch.default_headers = {
    "X-Frame-Options" => 'ALLOWALL'
}

my application.html.erb

<!DOCTYPE html>
<html>
<head>
  <title>Test</title>
  <%= csrf_meta_tags %>

  <%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>
  <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>

  <!-- HTTPS required. HTTP will give a 403 forbidden response -->
  <script src="https://sdk.accountkit.com/es_LA/sdk.js"></script>
  <script src="https://www.gstatic.com/firebasejs/4.6.2/firebase.js"></script>
</head>

<body>
<%= yield %>
</body>

I'm using RubyMine. ruby 2.4.1 rails 5.0.6