There were some fixes in 5.1.3 about this sort of error message
VMware vCloud Director 5.1.3 Release Notes
- vApp creation could fail on a heavily loaded system
When the system was operating under heavy load, new vApp creation could fail consistently with the error:Could not find object with moref "vm-xxxx" and VC ID "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx" in inventory category "VirtualMachine".This issue is resolved in vCloud Director 5.1.3.
