What are your temps? If they are low, such as 90/80, try bumping up 5 degrees. 95 warm side, 85 ambient. I keep my temps like this all the time(no finicky eaters either).

What size tub is she in? Anything bigger than a 6qt and I'd bump her down to the shoebox. You can always cover the front of the tub with a black pillowcase.

Also, pre-scent the room when you feed for at least 30 minutes. Try a live hopper mouse and leave it in for a few hours. Make sure she's covered up and the room is dark.