Rebalance Stuck on 1.8 after adding nodes (rebalance gets stuck even if ack_seqno is correct and has_queued_item is true and total_backlog_size > 1000)

Added 5 nodes to a 10 nodes cluster.

TAP stats from the node that has one tap connection stuck.
/opt/couchbase/bin/cbstats localhost:11210 tap |grep rebalance

eq_tapq:rebalance_725:ack_log_size: 248
eq_tapq:rebalance_725:ack_playback_size: 248
eq_tapq:rebalance_725:ack_seqno: 58249
eq_tapq:rebalance_725:ack_window_full: false
eq_tapq:rebalance_725:backfill_completed: false
eq_tapq:rebalance_725:bg_backlog_size: 0
eq_tapq:rebalance_725:bg_jobs_completed: 43790
eq_tapq:rebalance_725:bg_jobs_issued: 43790
eq_tapq:rebalance_725:bg_queue_size: 0
eq_tapq:rebalance_725:bg_queued: 43790
eq_tapq:rebalance_725:bg_result_size: 0
eq_tapq:rebalance_725:bg_results: 0
eq_tapq:rebalance_725:bg_wait_for_results: false
eq_tapq:rebalance_725:complete: false
eq_tapq:rebalance_725:connected: true
eq_tapq:rebalance_725:created: 5423
eq_tapq:rebalance_725:empty: false
eq_tapq:rebalance_725:flags: 93 (ack,backfill,vblist,takeover,checkpoints)
eq_tapq:rebalance_725:has_item: false
eq_tapq:rebalance_725:has_queued_item: true
eq_tapq:rebalance_725:idle: false
eq_tapq:rebalance_725:num_tap_nack: 0
eq_tapq:rebalance_725:num_tap_tmpfail_survivors: 0
eq_tapq:rebalance_725:paused: 1
eq_tapq:rebalance_725:pending_backfill: false
eq_tapq:rebalance_725:pending_disconnect: false
eq_tapq:rebalance_725:pending_disk_backfill: false
eq_tapq:rebalance_725:qlen: 0
eq_tapq:rebalance_725:qlen_high_pri: 0
eq_tapq:rebalance_725:qlen_low_pri: 1
eq_tapq:rebalance_725:queue_backfillremaining: 0
eq_tapq:rebalance_725:queue_backoff: 0
eq_tapq:rebalance_725:queue_drain: 58240
eq_tapq:rebalance_725:queue_fill: 0
eq_tapq:rebalance_725:queue_itemondisk: 0
eq_tapq:rebalance_725:queue_memory: 0
eq_tapq:rebalance_725:rec_fetched: 14710
eq_tapq:rebalance_725:recv_ack_seqno: 58000
eq_tapq:rebalance_725:reserved: 1
eq_tapq:rebalance_725:seqno_ack_requested: 58000
eq_tapq:rebalance_725:supports_ack: true
eq_tapq:rebalance_725:suspended: false
eq_tapq:rebalance_725:total_backlog_size: 10327
eq_tapq:rebalance_725:total_noops: 836
eq_tapq:rebalance_725:type: producer
eq_tapq:rebalance_725:vb_filter:

eq_tapq:rebalance_725:vb_filters: 1

/opt/couchbase/bin/cbstats localhost:11210 all |grep mem
ep_diskqueue_memory: 0
ep_mem_high_wat: 7864320000
ep_mem_low_wat: 6291456000
mem_used: 6270355533
vb_active_ht_memory: 25611040
vb_active_itm_memory: 4777690775
vb_active_perc_mem_resident: 32
vb_active_queue_memory: 0
vb_pending_ht_memory: 0
vb_pending_itm_memory: 0
vb_pending_perc_mem_resident: 0
vb_pending_queue_memory: 0
vb_replica_ht_memory: 17336480
vb_replica_itm_memory: 1221834713
vb_replica_perc_mem_resident: 11
vb_replica_queue_memory: 0