Why are we getting tickets with [No content] in the subject or description?
These tickets are most likely created by email. This can occur when the customer emails your support email address without content in the subject or body fields of the email. This can also happen if the body of the email contains unformatted content that is not supported by Zendesk.
Have the sender resend their message if it is not viewable in the original email source.
For another reason you might not see content in the body of the message, see this article: Updated ticket does not show any content from the customer.