If a user is unable to see the attachment you sent in a ticket, it is becuase the attachment is sent as a link to download.
On NVD, everything looks normal, but the user may need to set the sender as safe. After marking the email as coming from a safe sender, the links open in browser and immediately start downloading the file.
On ONE-Net, the links show up as large blocks of text, user must first choose to display as HTML before they can click to open the browser and download the forms. Note that user should download the "ORIGINAL" and not the safe copy.