Multiple tasks with resources assigned to some of them are displayed inside the GanttChart.
Those that do not have tasks assigned have a question mark. Projects are not allowed to have resources assigned to them, thanks to the disableResources property.
A formatFunction is applied to the "Assignee" column which displays tasks with multiple resources assigned in a different way.
The Resource Panel is hidden in order to see only the Tasks.

Switch view:

Resource View
Resource view displays groups the tasks according to their assigned resources. Tasks that do not have resources assigned are added to the "Unassigned" group. Resource groups are sorted alphabetically.