Websocket notifications: No notification received when data are removed

Tested data change notifications (via websockets, pcep-topology) - subscribed on network-topology

<input xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:remote">
<path xmlns:a="urn:TBD:params:xml:ns:yang:network-topology">/a:network-topology</path>
<datastore xmlns="urn:sal:restconf:event:subscription">OPERATIONAL</datastore>
<scope xmlns="urn:sal:restconf:event:subscription">SUBTREE</scope>
</input>

When data were created (added node to topology - pcc-mock connected), notification was send & received on client side. However when data were deleted (topology node was removed, pcc-mock disconnected), no notification was received.