Ok, so I've had AS engineers look at it and it all makes sense, there is a bug but only with the reported error message. This was interesting.
Here is their support response:
Hi Brad,
Thanks for following up with us regarding this matter! ...and I apologize for the confusion this issue has caused. As Sam previously stated, the "Unresolved Bid Group" status is usually returned when we snipe(A) becomes cancelled automatically because were unable to confirm the end-of auction status of the previous snipe(B) in the bid group by the time snipe(A) is scheduled to be launched. It also typically takes less than 30 seconds from an auction‘s end for us to confirm the end-of-auction status of an item, so your understanding that the end times of snipes in a bid group just need to be 30 seconds apart is also correct.
In this case, we were actually unable to place your bid on item # 220133893780 because the seller ended the item early. You can verify this by visiting the auction using the following link, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220133893780, where you will notice the message "The seller ended this listing early because of an error in the listing.". I ran this case by our engineering department and, apparently, the reason this status message is displayed next to the item is because the "Unresolved Bidgroup Item" is the default "failed snipe" status we display next to bid group items when the system is confused. This snipe really should have been stamped with "Ended Early" status, but we‘ve been having some problems with that status lately that we‘ll be addressing with a future release.
Sincerely,
Michael Davies
Customer Support Manager