The Resources section of your chart is split into two panels:
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Resources cannot be assigned to groups or milestones.
If an issue is treated as a group, any resources assigned to that issue will be ignored when calculating resource usage.
Backlog Panel
When using sprint-based scheduling with the Backlog panel visible, the resource requirements for backlog items will be displayed to the left of the Resource Usage panel. This allows you to quickly see how much unscheduled work has been assigned to each resource, so you can make adjustments before tasks are added to the schedule.
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