In a CA PPM cluster, the Health Report is showing an Invalid (red) status for the CSA item "Application Instance(nsa)" on nodes running an app service but not a CSA service.
Any CA PPM release.
The Health Report is not checking the whole cluster for the CSA status but the current node. If there is a node that already has a CSA service in the cluster, please check the Health Report connecting to the app service in that node instead. If connecting via a Load Balancer, the target node is generally unpredictable, so connect directly to the app address and port instead.
The error is safe to ignore when connected to the other nodes that do not run a CSA service.