This has reference to ticket vs project activity topic.

When the resource looks at the Gantt chart (Follow up > Planning screen), he cannot see the all his engagements in one place.
When the project manager looks at the Gantt chart, he does not see tickets.

Thus the Gantt chart paints only a partial picture about the work to be done.

Desired:
The Gantt chart for all users (both the assigner and the assignee) should show the tickets.
When all the tickets and project activities are shown on the same time scale, it gives the best idea about how they have to take up work.