I am seeing the same issue as the previous posters. Attachments from Canned Responses show as attached when used in a ticket reply, and are downloadable and viewable from the Post Reply dialog. Once the response is sent, the attachment does not make it into the ticket response or the email notification to the user. Manually attaching works fine.
This issue appears to be browser dependent. When using the SCP, Chrome (v92) and Firefox (v90) exhibit this behavior but Edge (v93) does not.
This behavior happens with both DB and FS attachment storage for us. osTicket version 1.14.2, PHP 7.4.