I do have access to Master’s but the ~10 times I’ve gone over the years I’m yet to ever get 1 iota of feedback.
Did you ask?
Think of it like a relationship. It takes time for coaches to see you, see how you respond to certain situations, and they might have 15 or 20 (or more) swimmers that they are looking after. My experience is that unless you ask, coach may divert their attention elsewhere. Remember, not everyone at masters wants feedback. Lots just go to get in a workout with friends.
To me, the big benefit of swimming masters isn’t so much the feedback from the coach, but from pushing yourself against other athletes.