Hi
My DD11 also has anxiety and has had phobias relating to various forms of transportation (e.g. buses and trains). I have to say - it's great that your DD is able to talk to the teacher and school counselor about it! My DD would have a lot of trouble doing that.
Is it possible that when your DD is with the class, she will feel anxious but end up going along with her peers on the escalator? Sometimes that might actually work. Would she be OK going on it with a special friend? Or holding the teacher's hand? Sometimes the teacher can find a way to do this without making a child stand out. If she were to refuse to get on the escalator, do they have an alternative plan (e.g. the stairs?)
With my DD, we were forced to take a more gradual approach to de-sensitize and help her get used to the things she was worried about. She developed her anxiety last year and on the first class trip she refused to even get out of the car when I took her to school. Next field trip, I decided to go along with her and sat with her on the school bus (not sure if going on the field trip is possible for you?). The one after that, she was able to sit on the bus with her teacher.
Practising something that is hard to do can be helpful - we did this with train travel (e.g. going just one or 2 stops, then going longer, and so on).
Is it possible for you to practise riding escalators with your daughter? Maybe start with just standing near the escalator; then try riding it - as many times as she is able to - ideally with gradually less support from you each time...
Also, is it something specific about the escalator that bothers her - the sound, the vibration? Is there any way to mitigate the sensory issues?
Good luck - I know how stressful these situations can be.
