I have the same issue with the ACI Simulation reservation. An addtional log entry from the output window:
07:04:21 ERROR: OOB Setup script returned errors
Driver:UDC_EnvironmentDriver_B
Function:call_OOB_setup_script
I see this in the Activity feed:
'OOB but set to type Default for 8.1' Blueprint command on 'ACI Simulator Reservation' failed with 'Script runner exited with exit code: -1' error
Execution Server: SJ-EXEC-04
Error: Script runner exited with exit code: -1
Description: VM: Gold-5-acisim-3.0-2k failed with: "The vNIC: "Network adapter 2" is already set with: "QS_dvSwitch_VLAN_2046_Access"", The object has already been deleted or has not been completely created