Email template case updates thread blank

$acase_aop_case_updates_threaded is blank in email, using latest release v7.10.

May be there a better variable to use. Is $acase_aop_case_updates_threaded the correct field/value to use to include previous case updates thread to include in case update workflow email when a case updated?

mysql Ver 14.14 Distrib 5.7.21,
PHP 7.0.22-0ubuntu0.16.04.1 (cli) ( NTS )
Apache/2.4.18 (Ubuntu)
Ubuntu 16.04 LTS

I have the same problem any solutions to this ? I on SuiteCRM 7.11.13