What is the file type of the attachments you’re trying to work with? I ask as .ZIP files will cause a blob container error as a browser will not open that file type for security reasons.
Along those lines, the Kinetic Client passes the file to windows and asks for windows “pick the app to open the file” using the windows file type associations. If it’s a special file type and the PC doesn’t have a viewer, or an association set, it will not open.
i saw several times when instead of PDF it sent jpeg with some error message like about licenses. Look inside that downloaded file, if it is jpeg/png, rename its extension and check what it shows.
And the only time I’ve experienced it, was after some windows update, the default PDF app was reset to Edge. Also, I’ve seen PDF-A documents from Europe cause this problem with the cheaper viewers like CutePDF.