XDCR+UPR : Rebalance during replication fails with "Unexpected response. Unrecognised opaque ~p (~p, ~p)"

Scenario
--------------
-Uni xdcr between 2 one node clusters.
-Rebalance in one node on destination during replication between source -> destination.
-Rebalance fails with the following error

Rebalance exited with reason {unexpected_exit,
{'EXIT',<0.18186.1>,
{wait_seqno_persisted_failed,"default",975,
4807,
[{'ns_1@10.3.4.189',
{'EXIT',
{{{{{badmatch,
[{<18638.6529.0>,
{done,exit,
{{badarg,
[{io_lib,format,
["Unexpected response. Unrecognised opaque ~p (~p, ~p)",
[978,

{mc_header,81,0,0,0,4,4, 978}

]]},

{'ale_logger-rebalance',warn,5}

,

{upr_consumer_conn, process_add_close_stream_response, 3}

,

{upr_consumer_conn, handle_packet,5}

,

{upr_proxy,handle_packet,4}

,

{mc_replication,process_data,3}

,

{mc_replication,process_data,4}

,

{upr_proxy,handle_info,2}

]},
{gen_server,call,
[<18638.5412.0>,

{setup_streams, [973,974,975,976]}

,
infinity]}},
[

{gen_server,call,3}

,

{upr_replicator, '-spawn_and_wait/1-fun-0-', 1}

]}}]},
[

{misc, sync_shutdown_many_i_am_trapping_exits, 1}

,

{upr_replicator,spawn_and_wait,1}

,

{upr_replicator,handle_call,3}

,

{gen_server,handle_msg,5}

,

{proc_lib,init_p_do_apply,3}

]},
{gen_server,call,
['upr_replicator-default-ns_1@10.3.4.188',

{setup_replication,[973,974,975,976]}

,
infinity]}},
{gen_server,call,
['replication_manager-default',

{change_vbucket_replication,978, undefined}

,
infinity]}},
{gen_server,call,
[

{'janitor_agent-default', 'ns_1@10.3.4.189'}

,
{if_rebalance,<0.16552.1>,
{wait_seqno_persisted,975,4807}},
infinity]}}}}]}}}

Observation
------------------

• Tried again during replication from source -> dest. Rebalance failed for the second time..
• Paused replication at source, rebalance proceeds to completion.

Cluster setup
---------------------
Source : 10.3.4.186
Dest : 10.3.4.188 <-- rebalance in 10.3.4.189

Adding cbcollect info.