How long do you leave the rat in there before you remove it? I've heard others say that their pythons will ignore the food for several minutes then return to eat.
My little Reggie started doing what you describe. He would wrap up the prey, then seemingly lose interest and start searching around the top of the tub like the dead rat was invisible. I'd remove it right away, thinking it cooled off, warm it up, and Reg would be launching out of the tub wildly to grab it and then end up losing it again. In his case, I found out his hides were getting in the way of him eating. He likes to do a lap or two around the tub, carrying his trophy while he eats. Once I removed the hides and water dish before feeding, he stopped getting frustrated and dropping the food. Haven't had any issues since.
PS- your PM inbox is full. =p