IF YOU ARE USING A CUSTOM TEMPLATE NOT BASED ON THE ADMIN BLEND TEMOLATE YOU HAVE TO MODIFY THE CODE SO IT SUIT YOUR CUSTOM TEMPLATE

In admin viewticket.tpl template look for

<input type="button" value="{$_ADMINLANG.support.insertpredef}" class="btn btn-default btn-sm" id="insertpredef" />

 

Add this code on top

{* Ticket Sensitive Data *}
{$SensitiveData}
{* Ticket Sensitive Data *}