issue accessing mounted device supporting OpenConfig BGP

when attempting to access the list of BGP neighbors on a mounted device supporting OpenConfig BGP (using http://controller:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/xrvr-a/yang-ext:mount/bgp:bgp/neighbors) I get a VerifyException "Unable to find base type for leafref node". If I go for one specific neighbor with e.g. bgp:bgp/neighbors/neighbor/192.168.101.2 I get "java.lang.IllegalArgumentException: Module reference cannot be NULL".

The OpenConfig BGP model has a list of neighbors keyed by neighbor-address. Neighbor-address is a relative leafref to "../config/neighbor-address".