In my experience, many times killing a prey item and not eating it can be a sign of stress. Their natural instinct is to kill a prey item, but because they are most vulnerable to predators while they're swallowing, so a stressed (or insecure) animal will kill and not eat.

Triple check your husbandry and maybe try a hide if you don't have one or a smaller hide if you do.

Just a thought.

-adam