Hi Jordan,
Are you using two survey forms? One survey to have users submit a sketch, and then another for users to review it via the Inbox?
There are currently some limitations with pulling down attachments (such as images) into an Inbox. While we can editing existing surveys, and add more attachments, we cannot edit or work with existing attachments.
If you can provide more information on your workflow, ideal outcome and current forms/setup it will greatly assist Rawan, myself and others in providing help.
Cheers,
Chris