I am w longshot....give her the benefit of the doubt and try to eliminate the possibility that she is, in fact, "lost" on what is expected. Horses are like people. If one has worked cattle a lot, it seems obvious and apparent what exactly one needs to do, where they need to be, and how they need to get where they want to be in order to move cattle. Yet, take a rider and horse that have never been taught
the gist of it - and they will scattered your herd all over he**'s half acre. My point...perhaps she just needs to look at the cattle more to "get it" and be confident as opposed to desperately trying to "guess" by taking her cues from other horses. Like longshot said, I'd try her by herself (under saddle, that is)...in a controlled situation w some calmer, slower moving cattle. I'd go a step farther...I'd put her in a large arena so it can be done "patiently"...there the cattle can't actually scatter to far or "leave dodge" all together. As you
know, cattles responses are highly predictable, in an arena she
could learn that, too.
Otherwise, if she never shows any indication of cow sense or willingness to go it alone, I'd think about using her for other chores.