I have a rule that says. When the user is in the Role of Scheduler, and customer field is equal to "n/a" make the customer field read only. Why, when I am in Admin role, is that field read only when I'm not in the scheduler role?
I would want to go detail-by-detail to compare the one that works as you want with the one that does not. (I expect you have done this, sometimes showing something strange to someone and explaining it helps me see more / different details.)
In a quick look, it seems that a rule similar to:
When multiple conditions are true the user is in the role B Customer = N/A