xray-rails not working with rails 4

xray-rails Ctrl+Shift+X is not working with Rails 4

Gemfile

group :development, :test do
  gem 'xray-rails'
end

development.rb

config.assets.debug = true

I bundled it

.
.
Using sass-rails 5.0.4
Using turbolinks 2.5.3
Using xray-rails 0.1.21
Bundle complete! 17 Gemfile dependencies, 68 gems now installed.
Use `bundle show [gemname]` to see where a bundled gem is installed.

Inspecting the element in browser with F12 shows me

<!--XRAY START 37 /home/sample/app/views/shared/_list.html.haml-->
<ol>
  <li>
    <strong>
      <a href="#">Link</a>
    </strong>
  </li>
</ol>
<!--XRAY END 37-->

NOTE: I am using xray-rails with rails 3.2 and it's working fine