I think you can be patient for a tad longer. When we moved in here I spied a mouse. I plugged the entrance holes to the flat (which I was aware of) and laid humane traps with peanut butter. Nothing for days. I renewed the peanut butter and put it back. One morning the trap had caught not one but two mice. That was it - no more since.
You know you only have one - so that's a bonus.
You'd hope it will get hungry and if you are not providing other sources of food (where's the cat fud at?) then the mouse will eventually find your bait.