These are known limitations for Filter & Dashboard Manager for Jira:

Must be parent to parent issue only

You cannot move sub-tasks to another sub-task.

Destination issue must be in the same project

Move and Copy options allow you to move and copy sub-tasks from one parent issue to another in the same project.

Deleted sub-tasks are permanent

It is currently not possible to recover deleted sub-tasks. The app prompts users to confirm the Delete function.

Struggling to manage sub-tasks in Jira? Try Sub-tasks Manager for free.

Sub-tasks Manager for Jira is available for your Jira Software instance today (Data Center only). Click here to try it for free.