Often the GUI leaves filesets on the Downloaded tab that might might be completed (if I can infer that by that I can rename/move the decoded files; don't laugh, that has been a reliable gauge), but Progress = 0% unRAR, right-click properties won't pull up a window. And I can't delete them; but the fileset then disappears if I close and reopen the program.
I've re-d/l-ed the installer and re-installed 6.80rc5.
I'll see if I can replicate this by re-d/l-ing a fileset this happened with. In any case, time it happens I'll followup with an offer to share the .nzb file via PM.