yes the version is 4.5.6
i tested it using your demo site and it seems ok. I hav a hunch it may have to do with the fact that ours is running windows
in your demo site it shows the filename as
/home/wdpownlo/public_html/demo/wp-content/uploads/download-manager-files/blablabla
on our windows server it shows as
c:\inetpub\wwwroot\support.domainname.com/wp-content/uploads/download-manager-files/blabla
notice the backslashes until the wp-content were they change to forward slashes and of course the drive letter
something tells me this has something to do with the filename being so odd. it