When the auction list contains an auction where the user is currently the highest bidder, esniper will sleep until that auction's ending time is reached. This will cause it to miss all auctions ending before that one.
The core of this problem lies in the compareAuctionInfo() function, which puts currently winning auctions in front of all others. This was probably done to ensure that the user does not end up with unwanted items. However, if, for example, the user wants to win five items and has manually put a bid on the last one ending, esniper will never bid on any of the other auctions, unless he gets overbid on that one. And even then esniper might miss all auctions in up to the next 24 hours because it went to sleep.