hooks – drupal ajax callback is firing only once

i have apply button in my drupal node edit form , i am using the form alter hook to add that button , when ever the user clicks on that button i am making an ajax callback to replace the text field value , it is working fine for the first time , but the second time it is not replacing the value .

   function course_form_node_items_edit_form_alter(&$form, FormStateInterface $form_state) {

  $form('apply') = array(
      '#type' => 'submit',
      '#value' => t('Apply'),
      '#weight' => '38',
      '#executes_submit_callback' => FALSE,
      '#limit_validation_errors' => array(),
      '#ajax'                     => array(
        'callback' => 'button_test_callback',
        'wrapper' => 'edit-field-text-plain-0-value',
      ),
    );

}

function button_test_callback(&$form, FormStateInterface $form_state) {

  $item_id = $form('field_item_id')('widget')(0)('value')('#value');

  $sql = "SELECT  item_name
          FROM items
          WHERE  field_item_id = '".$item_id."'";

  $location = Drupal::database()->query($sql)->fetchAssoc();

 $form('field_text_plain')('widget')(0)('value')('#value') =   $location   ;
  return $form('field_text_plain');
}

I see the after the first click the form_text_plain id changes to some random value like edit-field-text-plain-0-value-xhfjwos , it looks like that is the issue , is there any way we can stop it from changing ?