vCenter Server UI > Inventory > Resource Pools > Summary Tab, you may notice that the Custom Attributes card is missing. This behavior is only to Resource Pool objects. Other objects in the vSphere inventory correctly display Custom Attributes in their Summary view:This issue is due to a product limitation where the Custom Attributes UI component was not associated with the Resource Pool Summary page in current versions of vCenter Server.
This is a known issue in vSphere vCenter.