We're having problems when customers are uploading larger files because there is no progress indicator, so they think the upload isn't working and leave the page, which then seems to leave the partial upload stuck in processing forever. If we could have a progress bar, or even a message not to leave the page until the upload is finished it would be a big help
Yes this would be a big help and should really be added. This should also be the case in Pressero when a customer is adding an item to their shopping cart and as the upload artwork field. Even in that field it just shows a progressing artwork bar instead of a percentage so customers can often abandoned a checkout.