Not sure what version of vROps you are running but maybe this helps:
A vCenter Server user is a read-only principal in vRealize Operations Manager, which means that you cannot change the role, group, or objects associated with the role invRealize Operations Manager. Instead, you must change them in the vCenter Server instance. The role applied to the root folder applies to all of the objects in vCenter Server to which a user has privileges. vRealize Operations Manager does not apply individual roles on objects. For example, if a user has the PowerUser role to access the vCenter Serverroot folder, but has read-only access to a virtual machine, vRealize Operations Manager applies the PowerUser role to the user to access the virtual machine.
As to the problem with local users, when you run the report in the "Select an object" drop down are you selecting the vSphere World under Hosts and Clusters or from another selection? i.e vSphere World under Networking.