Hi,
We have some existing tasks that are under 'issues without subtask' in our Board. We want these tasks be subtasks of an existing story. How would we give these tasks a new parent story?
Below a screenshot to illustrate the issue.

What we've tried:
- Click the issue and click: Choose Parent. This does not work as it does not show any results as it expects the parent of a Task to be an Epic.
- Click the issue and click 'Task' in the top left in an attempt to convert the Task to a Subtask. It only allows issue to be changed to Epic or Story even though Subtask is clearly a defined issue type for our project
- Click the issue and click Move. Here the UI gives the impression that you can actually change the Task to a Subtask and choose a parent. However, the so called 'bulk' change throws a generic error.
How do we achieve this without adding a new subtask to an existing Story? Thanks in advance.