When you're curious why sometimes attachments in tickets offer two options (buttons) and sometimes not (the "View" button is missing), you're on the right place. Because here you can find an answer. These two buttons, allow you to download or view attachments. Below you can see the certain content-types that support the "View" option.
audio/* video/* image/* except svg
viewable by google viewer:
application/msword application/vnd.* application/pdf
The content-type without "View" option --->
application/octet-stream
Who is responsible for the content-type header setting of attachments? ---> That is exactly the application that sends the email message. And LiveAgent just accepts and reacts the following way = displays the "View" option or not.