Rebalance exited with reason unexpected_exit ( rebalancing cluster with xdcr and views )

Test case:
xdcr unidir (east->west), 1 bucket per cluster, 10M x 2KB items per cluster, 3 ddocs (8 views), mixed workload with queries.
rebalance from 3<>3 to 4<>3

From logs:

Rebalance exited with reason {unexpected_exit,
{'EXIT',<0.12156.402>,
{{badmatch,
[{'EXIT',
badmatch,{error,nxdomain,

{gen_server,call, [<18120.6681.401>,had_backfill, 30000]}

}}]},
[

{ns_single_vbucket_mover, '-wait_backfill_determination/1-fun-1-', 1}

]}}}

<0.11203.402> exited with {unexpected_exit,
{'EXIT',<0.12156.402>,
{{badmatch,
[{'EXIT',
badmatch,{error,nxdomain,

{gen_server,call, [<18120.6681.401>,had_backfill,30000]}

}}]},
[

{ns_single_vbucket_mover, '-wait_backfill_determination/1-fun-1-',1}

]}}}