Sorry I have not followed your previous difficulties at this facility.
I still think you need a face-to-face with this person, tell them they are being arena rude, need to look out, avoid others using parts of the rail at times.
You can try meeting her in the aisle, on foot, do the polite thing. Explain left-to-left, who gets the rail in if slower or faster. NOT cutting into another rider’s circles. Hope that works for you. Just complaining to us, muttering as you “give up”, won’t change a thing. She obviously hasn’t a clue about being in the wrong.
If no change, no help from BO, then you have to step up your game. Guess I am not willing to put up with other people’s BS, which is causing problems. I will yell ahead of passing, warn of my path, so they can get out of the way or be aware that I AM going to be close to them so they can do “whatever” while I get my planned ride done. Might also be rude at times, but some folks just won’t change without being pushed to do it.
But I am not a shrinking violet. Though I have never boarded, when using arenas at clinics, warmup arenas at shows, public arenas, I have had to deal with “stupid” and her friends also using them. I try polite first, but such unsafe conditions will quickly make me “do something” to improve things. Your comfort levels may not be like mine in getting her attention, changes made. You can lay down and take it or work for change. MAYBE she will start to ride at another time to avoid you! Ha ha Good luck.