When adding a gallery to a post/ page I make sure to check the option to link to the file rather than the attachment page, however it doesn't add the needed...
...attribute to the inserted gallery.
If I then go back and edit the gallery, change the option to link to the attachment page, save it, and then go back yet again and change it to link to the media file (and save it one last time), it then adds the needed attribute.
Of course on my own sites it's easier to just add in the attribute manually in HTML view, however on client sites (where most don't have access to HTML view), that's not possible.
Anyway, looks like a bug to me so just thought I'd make you aware.
On the whole though, thanks for a great plugin