Add a Checklist to a Subtask on Issue Creation

1. Go to Project Settings → Automation → click Create rule

2. Create a trigger

2.1. Choose Issue created 

2.2. Save trigger

3. Add sub-tasks to the Issue

3.1. Add component: Add an action

3.2. Choose Create sub-tasks

3.3. List subtasks you need

4. Add Checklist to the sub-tasks

4.1. Click Add fields - your subtask will be converted to a separate action step

4.2. Choose Same Project to be sure the sub-task is not lost

4.3. Add Checklists custom field from Choose fields to set

4.4. Add template using checklist Markup formatting

4.5. Save action

5. Name your new Automation and Turn it on

You're done! Now every time an Issue is created new sub-tasks with Checklist Items will be created automatically 🎉