Why Do Only One Resource Instance Appear When Reporting a Resource Transaction in a Work Order?

In Oracle Fusion Cloud, I created a resource with three resource instances and assigned it to a standard operation. Then, I created a work definition using this standard operation. However, when I generated a work order and attempted to report a resource transaction, only one resource instance appeared instead of all three.

I expected to see all three resource instances available for reporting. What could be causing this issue?