Few of our operators are facing an issue while accessing the attachment from the change ticket.
Error: Sorry, you are not authorized to access the specified resource.
have you figured it out coz I am facing the same issue, not for all tickets. and it is not a user privilage coz same operator can access other tickets' attachments normally.
Check the user profiles who are experiencing the issue and compare it against one currently working fine.
Also make sure the attached files have valid names with no special characters in their names and also make sure they have no extra "dots" like "file..msg" since this can cause this error: