VMware Cloud Director 10.6.x
The custom role was missing "Administrator control" rights but had "Administrator view" right.
"Administrator view" right allow users to see any managed object for other users."Administrator control" right allows users to manage any objects owned by other users inside an OVDC.
To resolve the issue, the "Administrator control" right can be added to the custom role. Follow steps in Edit a Custom Tenant Role
Once the right is added, verify the objects owned by other users can be managed successfully(open VM console, power operations etc.)
To compare rights in the custom role to a default role available, refer Rights Included in the Global Tenant Roles in VMware Cloud Director