Forgive if this is a repost, I did search the forum before creating the topic, and didn't find anything pertaining to this particular "feature." Using ver 6.30 build 1832.
Downloaded a rar set that was chunked into 20mb chunks, which turned into a HUGE list (400+ individual files) which naturally the rar creation turned the suffix files to s00-99, t00-99, u00-99, and so forth.
Where the error comes in is the deletion of the archive after it's been processed by Newsbin. It ignores the files that aren't r## suffixed, and they'll sit in your directory until manually deleted. Scared the bejeezus out of me at first, I thought it had only processed the partial list then deleted. Not the case. It WILL unpack normally, or at least it did in this case.
Wanted to bring this to your attention in case it hadn't been found yet.