I've never had a problem with my cat using the litter box. I was always told that if cats don't like the litter box, its usually because they have issues about being declawed OR they are sick.
My suggestion is just to keep it in an obvious place, or maybe you even need to add an extra litter box to your apartment or house so that she has an easier time finding it when she needs to go.
Also, you maybe could also spend some extra intense play time with her in the evening. Sometimes, its' not about being home with an animal all the time, but spending quality time with that animal when you are home.
Me and my bf work all day, and we have a cat and a dog. However, we don't have children and are able to spend time wearing out our animals.
If you have currently done all of these things, then I am all out of helpful advice. Maybe some cats are just like that.