I've noticed recently that some NZB files I've downloaded have no file extensions (.rar or .par) and therefore newsbin isn't automatically unraring them. Autopar is enabled as well. I noticed during a download of one of these files that Newsbin did tell me which files were par files. So when the files finished downloading I added the .par2 extension to the proper file, ran it in quickpar and it renamed all the files appropriately and I was able to unrar manually. Not sure if this is a new trend among uploaders for obfuscation but it seems to be preventing newsbin from unraring automatically.
More info, the subject shows a different name than the filename. Filename has no extension, the subject shows extensions (rars and pars). The Newsbin log shows me this
[01/13 21:45:16] DEBUG NNTPServer: Post doesn't seem to be the post requested :667510cc602e4f6aa551d79a88d5412e "667510cc602e4f6aa551d79a88d5412e.part01.rar" yEnc - kx8zv0-r7Dn_UUIOBywxImA1KPy9GHaR-5X8rh6PgR1_