This was reported in the associated forum URL. Checking the code it seems that the logic is ...
If the session is remote, then
will return null.
[Edit; correct description following feedback on forum]
Description of class LocalRoutingTable says:
"Internal component used by the RoutingTable to keep references to routes hosted by this JVM. When running in a cluster each cluster member will have its own RoutingTable containing an instance of this class. Each LocalRoutingTable is responsible for storing routes to components, client sessions and outgoing server sessions hosted by local cluster node..."
So because remote routes are not synched over the cluster members it will always be null?