It’s time to pull out the big guns – - - BLEACH! Is this a concrete floor? You may need to soak the offending area in strght bleach…
It’s vinyl tile. I can definitely try bleaching it.
Don’t go crazy switching things around and changing too many things at once or she can get confused, or territorial.
How old is she? Could she maybe have a bit of arthritis and it’s uncomfortable to climb over the edge?
Other than Nature’s Miracle, I’ve heard good things about plain old vinegar and backing soda. Don’t use anything with ammonia in it. And beware of those bitter apple sprays. They smell ok in the bottle at first but whew! They pack a stinky punch when you go to use it, and it hangs in the air for over a week! I don’t know what’s in it, but there’s this stuff that’s a green gel you put in your garden to keep neighborhood cats out of your flowers. Maybe that could be used to drive her from a favorite naughty spot. And there’s always the double sided tape and prickly pine cone trick too.
And maybe put some aluminum foil or cardboard covered in double-sided tape down over that spot. Cats don’t like that and it’ll keep them away until the habit is broken.
StG