There is some question* as to whether eBay has changed the Second Chance Offer process recently to allow sellers to make multiple SCOs but limit the number that can be accepted (e.g. first to accept gets it if you only have 1 item to send out); note however that this would not work where you have a single item until the winner's transaction has been settled (e.g. cancellation after 4 days for non-payment) since the winner can still pay and be entitled to the item until the cancellation is done.
The other possibility as to what you describe is that none of the losing bidders has their Communication Preferences set to receive SCOs, in which case the option is not available to the seller.
*The Help Page for making SCOs https://www.ebay.com/help/selling/listings/selling-auctions/making-second-chance-offers?id=4142&st=1... notes that the seller can specify the quantity of items available but don't say what eBay does with that information; posts in the past few days suggest that the SCO to a bidder expires when other bidder(s) accept their SCO using up the quantity specified; but the Help Page still contains the old language to not have more SCOs outstanding than the quantity available. So who know other than the coders who set up the SCO process at the last revision??
