I believe this is the same bug that Hari saw.
Here are some logs from a 2 node ONOS cluster.
Steps to reproduce:
Start ONOS nodes
Assign devices to all nodes in the cluster (At this point, topology is correctly discovered)
through ONOS1 cli send "device-role of:0000000000001000 10.128.30.12 master" (ONOS 1 was the current master of this device)
At this point 2 links disappear, it looks like each is a unidirectional link connected to the device that changed mastership.
It looks like the master of of:0000000000002000 is 10.128.30.11 and the master of of:0000000000005000 is 10.128.30.12