If the grains section of the cloud.saltstack section of a Aria Automation blueprint is defined by a vRO workflow then it appears that no grains get actually placed on the VM. It may be that the workflow is not returning the data in the expected way or there may be some corruption of the date by the workflow. Either way when the machine is deployed it has no grains.
salt - 3006.9
Aria Automation - 8.17
Aria Automation Config - 8.17
Define the grains in the cloud.saltstack section directly rather then have them defined by extensibility.