I'll chiming in with the same. Either move her to a 15 qt or if you have the dividers for those tubs, divide one. Give her a good, solid week to adjust to the smaller area, pre-scent and give it a try again.

I have three females that are big enough for 32 qts easily. If we move them out of the 15 qts though, all three immediately refuse to eat for weeks on end. Put them back in their beloved 15's and it's....WHAPPP.....WHAPPPP....WHAPPP...dinnertime!