I have a Kanban board in a company-managed project.
When I go to the Timeline view - I am expecting that I can add individual issues to the time line by clicking on the horizontal line and dragging a box to set start date and end date. However, I can only do this on certain issues and I don't understand why.
For example, I can click next to the Epic ticket to set the start and end date (red box) but I can't do the same for the child issue under it. 
I am expecting to be able to create a full timeline with start and end dates for each issue in my epic. How do I do this? Do I need specific permissions?