I usually listen for the "squeak"...for all you know, it might be curled up with the snake, as the warmth feels like it's mom. I would check.
Also, I disagree with the "know-it-all" guy...I wouldn't drop them on top of a shy snake. One thing you might try with a live fuzzy is: put a tip-proof
heavy bowl in the cage (flat bottom & at least 2" deep) and leave the fuzzy in the bowl. It will crawl around but not escape. Your hungry snake should
likely follow the scent & not be put off by a clueless mouse that seems to approach it. Snakes instinctively feel braver when they have the "upper hand"
and can look down upon prey wiggling past them...like from a ledge, only this "ledge" will be the edge of your bowl. The added bonus is that the mouse
will be easy to find & you'll know the answer without a cage search.
Another thing you could do is to set up exactly as above ***while the snake is IN the hide***- putting the bowl w/ fuzzy near the hide opening so you can
put an empty cardboard box over both the bowl & the hide w/ snake...this will help the mouse scent waft into the hide, and give more privacy overnight.
It's an easy check to just lift the box next morning to see in the fuzzy is still in the bowl or not, without invading your snake's actual hide.
I have used the fuzzy-in-a-bowl trick before with success, & I hope it works for you. (some pet stores do their own "version" by putting both snake and
live prey in a paper bag & closing the top overnight...but that won't work for all snakes, especially since you have to handle the snake first to do it, and
it's a little too close for comfort for some of them...it's similar to the guy dropping mice "on" the snake...either one is too much like the prey approaching
the snake, instead of the other way around, and as happens in nature.)