I've been going through the same with my two baby ball pythons I got earlier this month.

Leaving the food item over night worked, except last week when one of them refused.

I'm am trying to get my snakes to accept being moved to another container then fed, so this week (today is feeding day ) I moved one to a container and really had to work with it my moving the dead mouse around and lifting it by the tail half way every few seconds, and that enticed the snake to eat.

The other had to be given a live mouse, which I hope to avoid next week.