I also was diagnosed over 2 1/2 years ago. I have never been able to cough up any mucus no matter how hard I’ve had tried. When I spoke with my pulmonary doctor and infectious disease doctor, they told me that that was very common, and not to force it. They said I would do more damage if I tried too hard. And not to worry about it they just said to keep the airway clearance to keep things moving around to try to avoid infection.