This is expected behaviour in vCloud Director for Service Providers.
When a VM group is assigned to a vApp Template VM vCloud Director will attempt to retain this configuration on any vApp VMs deployed from this template.
In a vCloud Director environment with multiple ESXi host clusters, the VM group that the vApp Template VM is a member of needs to exist on the destination ESXi host cluster backing the Organization VDC where the vApp VM is to be deployed.