What is the reason for Huawei mate7 SMS to display attachments?

Reason: The other party has sent you a short message with an attachment (such as a picture) in the short message history, so there will always be an attachment displayed in front of your short message preview screen.

Method of deleting attachments: Delete the short messages with attachments (such as pictures) sent by the other party in the short message history, and the attachments will disappear.