Yes. Config issue. This was/is said for DEs.
In particular, DEs with global full-featured settings managers from different design languages don’t like each other. Most, if not all, WCs and WMs don’t have full-featured settings managers, so they work okay with each other.
But yes, it would work if you use a different user account, and it would work for her as well. It’s just that some WCs/WMs won’t display things properly without setting them up correctly.