Epic swim lane name disappears when only sub-tasks on Work board

Steps to reproduce:

1. Create an Epic
2. Create an issues with subtask
3. Assign the subtask, and leave the parent issue as unassigned
4. Configure the swimlane based on Epic
5. Go to Work Mode and click on the quick filter "Only My Issue"
6. Notice the Epic swimlane is missing since the parent task is unassigned

Note: Some users use the story as a requirement page and work on the sub-task instead. This behavior causing user unable to track down from which Epic the sub-task belongs to.

See below:

Then

Expected behavior:
The swimlane shouldn't be missing when the quick filter is activated, although the parent issue task is unassigned