Sounds like there is too much room for her. Make it smaller to where she has to lay in it if she goes. I've found they wont do that
Should I make it smaller if she has to be in there for almost 12 hrs on the days I work?
Some dogs will actually de-sensitize themselves to the mess. Doesn't bother them one bit to lay in it. They assume someone will come clean it up. I've found I have to go the exact opposite way to fix it. Stick them out in the yard where they learn to like being clean (maybe muddy, but not poopy.) Once they live life in the 'clean lane', they are reluctant to go back to filthy living.