Using the "old" issue view, sub-tasks can be added to Epics using the "more(...)" button at the top-right of the screen.
There is no way to add sub-tasks to epics using the new issue view.
Jira Software cloud
- Enable the new issue view
- Create a Jira Software classic project
- Add an Epic to this project
- Click more(...) at the top-right of the screen
The option Create sub-task is visible
The option Create sub-task is not visible
There is no current work around