Ticket replies from agents go into the thread as 'empty' -- showing '(empty)' instead of the content -- especially when using canned responses or AutoHotkey-generated text.

In v1.18.3 this is caused by a change to htmLawed.php that strips certain content during sanitization. Workaround: replace the htmLawed.php file in v1.18.3 with the version from v1.18.2 (from the osTicket GitHub at the referenced PR: https://github.com/osTicket/osTicket/pull/6910). After replacing, restart the webserver and PHP-FPM to clear file cache. The issue is environment-dependent due to fastcgi_finish_request() buffering behavior.