First, always keep in mind that Canvas does not have email, and this is important because thinking of it as email can lead to expectations of email functionality. This guide How do I attach a file to a message as an instructor? states that
"Attachments appear in your user files in the Conversation Attachments folder and count against the files limit for your account."
You can see this folder in my own Files area in the screenshot below..............
As you can see, this is just one example of how Inbox/Conversations is not email.
Hi @diana_nanos Welcome to the Canvas Community. The attachment in your Canvas Inbox should be at the bottom of the message, somewhat as what is illustrated on the very last screen capture on this guide: How do I attach a file to a message as an instructor?
However, there has been a long-running issue with attachments sent from external email clients. IF your TA was replying to a message that you had originally sent via the Canvas Inbox and was using an external email client (such as Outlook) then the attachment will not go through. My guess is that this may be what happened in this case. While this should have been somewhat explained within the message itself, not everyone will spot it. You may be interested in voting up this Feature Idea: https://community.canvaslms.com/ideas/4746-attachments-to-inbox-from-external-email . I hope this helps, Diana!
(Oh, and see @kmeeusen 's better explanation of how Canvas works, above! )
Hi @diana_nanos ...
Both @kmeeusen and @kblack have given you great responses. Rather than marking one of their answers as "Correct", I'm going to mark your question as "Assumed Answered" because they've both provided helpful information. However, if you feel that you'd like to mark one of their responses as "Correct", please feel free to do so.