The list contains only provider VDCs that the system administrator granted for this organization. Select a provider VDC from the list or contact your system administrator if no provider VDCs appearVMware Cloud Director 10.6.x
The issue is caused by the tenants getting promoted to Sub-Providers after the upgrade to VCD 10.6.x. Sub-provider organizations need grants before they can create any tenant VDCs.
To resolve the issue, there are 2 options: