Did you try specifying by using labels? 

https://docs.kasten.io/latest/usage/protect.html

cheers

Before creating the policy itself. If I look at the details of an application (namespace) under the workload it doesn’t show up replicasets. 

yes you are correct. I have never tried this myself. It could be due to the fact that deployments are hight in the architecture and have more features like updates and versions but I am just guessing here. I good overview here. The kasten support folks will chime in, might be a more obvious reason that I am simply missing. 

https://www.baeldung.com/ops/kubernetes-deployment-vs-replicaset

cheers

Forgot to add that I did try and did a restore but it did not restore the pods and no artifacts.