We only add estimates to subtasks, and not to both subtasks and parent tasks (stories.) This helps us avoid double counting of issue totals on Jira reports and pages. Unfortunately, there isn't a good way to group changes outside of an issue type such as epics or subtasks.

The Jira issue page has an option to include subtasks when seeing the original estimate. This would be helpful on the Details View while using the Agile boards. My stories with subtask estimates are showing 0 under the Estimate field; however, they are showing xx hours under the Remaining field. So, it's misleading that the "Estimate" field only shows the estimate for the main task or story; however, the "Remaining" shows the total remaining for subtasks as well.