Hi James,
From your description, it appears that the process has been timed our or killed off.
Please contact your hosts/server admin and have them check the PHP error logs. These logs should contain a record of the exact information as to why the process could not complete
Alternatively, you can manually restore the uploads.zip file via FTP. Download the uploads.zip, extract the zip on your computer and upload it to ‘wp-content’ directory so it becomes ‘wp-content/uploads’.
Kind Regards,
Bryle