Why is my Ajax callback not returning anything?
there are a few things that could go wrong with this. Ajax callbacks can be a really hard thing to do and often requires a bit of trail and error. Hope this helps.

First of all, when your ajax callback function should not contain the "::".
This is only used when you are programming inside a Class, right now you're in a .module.
So you can change to. 

'callback' =&gt; 'some_ajax_sample'


Furthermore you should check with a breakpoint if you even get inside the function. This should be resolved when removing the ::. 

Second thing you should do is add the wrapper div to your element.
You can do it like this:

$form['elements']['name']= [
  '#prefix' =&gt; '&lt;div id="edit-name"&gt;'
  '#suffix' =&gt; '&lt;/div&gt;'
  '#type' =&gt; textfield,
  '#title' =&gt; 'sammy',
  '#ajax' =&gt; [
            'callback' =&gt; 'some_ajax_sample',
            'wrapper' =&gt; 'edit-name',
            'event' =&gt; 'keyup',
            'progress' =&gt; [
              'type' =&gt; 'throbber',
              'message' =&gt; 'loading.....',
            ]
          ],
        ];
}


When you added the wrapper, Drupal knows which element should be replaced and update.

Last thing you can try is to remove the response and to just return the $form['elements']['name'].

Hope this helps.