Change 19156 appears to be causing some core flows stuck in PENDING_ADD state. This is always reproducible by restarting one ONOS node.
Taking arp flows as an example. It seems most arp flows stuck in PENDING_ADD have org.onosproject.provider.host as appId, while the ADDED arp flows have org.onosproject.neighbour as appId.
See attached onos-diags for more details.