I recently set my notification preference, and enabled the AuctionCheckoutComplete Notification along with other notifications on eBay Sandbox using API version 775.
I got a successful response and I am receiving notifications for all except the AuctionCheckoutComplete Notification.
Don't know what I am doing wrong. I completed the entire checkout flow and purchased items of both Auction and Fixed priced type listings successfully. However, the AuctionCheckoutComplete notification does not seem to be sent by the sandbox.
I would really appreciate any help with this.