When I have had problems that extreme with eye focus, it has usually been a developmental issue (I have a boy now, on the spectrum, always looking away, I consider it a victory if I can get him to mostly look at his partner during a scene). If it is, tread lightly, and know that she may never be able to do it, but praise her for the effort and for every little bit she does. If it is not developmental, and it is not corrected by what you have done so far, it is probably emotional. Again, tread lightly, but maybe start by having a private one on one discussion with her about it - why does she think she can't put her focus where it needs to be?
Sorry, that's not an answer, but I hope it helps. It's the sort of problem, where if it isn't fixed just by a giving the note a few times, then it is usually an expression of a larger issue.