Sub-tasks are supposed to inherit the security level of the Parent task. If the Parent task's security level is changed such that a second user can't see it, the Sub-task should be hidden as well.

What's happening is that the Sub-task is still being shown. If you secondary user attempts to view the issue, he is denied.

To recreate the issue, do the following:

1. Create two security levels in Issue Level Security
   1. Private: Admin User only
   2. Public: jira-user Group
2. Create a Parent Task, and a Subtask
3. Make the Parent Task Public
4. Confirm it's visible in the Issue Finder by another user that is not Admin
5. Change the Parent Task to Public
6. Use the Issue Finder by another user other than Admin and the Subtask is still visible (although the Parent is not).
7. If I attempt to open the Subtask, I'm denied permission.