Why do some of my Epics not show the expand / collapse icon? I have checked the epics and they do have stories, tasks etc as child items (so not at subtask level) - but there is no expand / collapse icon to show these.
Steps to Replicate
Create a timeline in JIRA, and add the filter "C24"
The result show as follows, where two out of the six items do not have the expand / collapse option, and all "Type" options are deselected by default

When I then select all "Types" options it displays only the items with the expand / collapse option. Given Epic A and Epic D do have Stories and Bug tickets etc - why do they not show on this list with the expand / collapse button?
Note all epics and tickets created at story level are from the same JIRA board.
