bulk download all chapters of a course in itunes u app

I am having issues with bulk downloading all chapters of courses through iTunes u app. some course consist of mulitple chapters 20-30+ and I am interested in downloading all chapters of the course by clicking the main course download button instead of individually clicking the donwload button on each chapter.

the overall course download course is not initiating downloads but the button color changes from grey color to green. It have been tested the iTunes U app on both iPhone of iPad

clicking individual chapter downloads work.

any idea about this issue?