As I understand it, when you place a bid through AS, eBay's response goes back to AS. I know for a fact that AS has only a limited number of "canned" explanations for why a snipe failed or wasn't placed. When eBay, for whatever reason, fails to process a snipe AS will continue to show "ready."
I think in the situation you describe I would file a support case at http://support.auctionsniper.com/ and let the techies look at it. I still am of the opinion that in one of the cases you mention your bid was not one increment higher than the current bid, and thus failed, while in another the current bid was clearly one increment higher than your bid, which is known as "being outbid." Incidentally, you don't know how high the winning bidder's max actually was; eBay only shows an amount sufficient to top your bid.