Receive notifications of new posts in iTunes U but can't see them in app on iPhone.

I created a course in iTunes U. It works well on my iPad, but when I create new posts there or in Course Manager on my Mac, I can't see the posts on my iPhone. I get notifications of the new posts, but when I open the app, it hasn't updated the content. The only way I have been able to refresh the content on my iPhone is to delete the course and redownload it, which I'm not going to do every time. I'm worried my students will have the same problem. Has anyone encountered this issue? Thanks