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
For v5 and higher you don't need to do any editing
For older version
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 *}