We just got Capacity Tracker and planned our first Sprint using this tool today. Our Scrum Master was able to see the individual capacities adjusted as we went assigned stories. However, whenever any of the other team members view Capacity Tracker, it shows each developer with a completely empty availability bar, as if nothing as been assigned to them. It also did not update their days off or estimated daily dev hours, according to how we set them during Sprint Planning. The Scrum Master seems to be the only user that can see the accurate tracker.
