I agree with all the previous comments and would also suggest that perhaps for the first few days to try to block off your hallway so she cannot access it. It’s probably inconvenient for you, but I think it would help her get the message and break her habit while you try to get rid of the odor.
My 10.5 yo basenji also has bowel issues (he was never officially diagnosed with any condition) and he has been on an extremely restricted diet for nearly his whole life. When he was younger one rainy winter he started pooping downstairs bc he hates getting wet. We blocked off the stairs while we thoroughly cleaned the area that was very effective.
Another suggestion I have if your dog loves food is to use her special kibble as treats. It works v well for us. Good luck!
L