Initial sync doesn't survive sync source's state transitions in 4.0 or older. Under this test's settings, I think it is always possible for a node to step down while another node is still syncing from it. This is because when at least two nodes are available, primary could step down if the other node has higher priority. And if the third node is still in initial sync, then the initial sync will fail. A potential fix would be to set a higher numInitialSyncAttempts (currently set to 1) for this test. And I think this could happen with PV1 too.