Problem Definition

With the latest release, JIRA v1000.456.2, the Kanban Backlog is showing the subtasks in Backlog.
Customers that were previously using Backlog on Scrum Board, expect that subtasks should not be shown.
Customer says that having subtasks in Backlog makes planing difficult.

Suggested Solution

Remove the subtasks form Kanban Backlog

Workaround

Use a filter for the board that doesn't show sub-tasks

project = "Project Name" and issuetype != Sub-task ORDER BY Rank ASC

Note: Because of the filter used, the subtasks are not shown in the Kanban Board neither but there is a note in the Issue Detail View.