Supplier Portal Attachment to Information Requested Unable to Open

The internal team has requested additional information from the Supplier in Supplier Portal (ie W9 information to verify tax information), and when the Supplier uploads the requested information, the attachment is, at times, not readable. When reaching out to the supplier they are saying the file loaded was a .pdf file type. The screenshot below is an example the profile change request where they request additional information and how the file is downloaded when attempting to download. Is this a bug or does anyone know of a setting that will assist with downloading this type of file loaded? Keep in