Gantt team board does not display my child's issues

Question

Hi, 
I'm currently working on three different projects. The first project is project management, where I'm creating EPICs (Epics are large scale projects that are broken down into smaller tasks). The second project is software engineering, where I'm creating stories for developing the EPICs. The third project is testing, where I'm creating tasks to test the EPICs. When creating a Gantt chart from a project management board, it is not reflected the hierarchy of an EPIC
This Epic has 2 childs story task.

elham_qksfkf · Answer

elham_qksfkf · Answer

Yes , they are Child of the EPIC

Ditte Simard · Answer

Are the Stories actually child issues of the Epics or are they linked in a different way?