This is due to the primary category not being set. In order to have the more details text in a notification work correctly, you must choose a primary category.

To set a primary category, go to onMessage:
  1. Select Content
  2. Then select Announcements
  3. Click on the Category that houses the Announcement
  4. Edit the Announcement
  5. Scroll to the bottom and mark the radio button under Primary
  6. Click Save
where to mark the primary category