In hierarchical route-reflectors setup when "local-as private" is used over IBGP session between RR (route-reflector ) and its clients , some IBGP attributes (i.e cluster ID and Originator ID )are not propagating properly by the RR.

in the below topology R1(RR-client ) advertises prefix (x.x.x.x) to R2(RR) then R2 should advertise this prefix to R3 and attach some IBGP attributes (i.e cluster ID and Originator ID ) . But according to the current design of this knob, R2 will advertise this route to R3 without these IBGP attributes (i.e cluster ID and Originator ID)

R1--------------------------------(RR)R2----------------------------(RR)R3
|-------------IBGP-----------------|-------------------IBGP-----------|
Primary AS1111                  AS2222                          AS2222
Local-as 3333                   Local-as 3333

R2 and R1 are configured with the below knob over their IBGP session

set protocols bgp group <*> local-as 3333
set protocols bgp group <*> local-as private 

on R2:

user@R2> show route x.x.x.x advertising-protocol bgp <R3> detail  
inet.3: 5 destinations, 6 routes (3 active, 0 holddown, 2 hidden)
  x.x.x.x/x (2 entries, 2 announced)
BGP group <*> type Internal
     Route Label: LLLL
     Nexthop: Self
     Flags: Nexthop Change
     Localpref: 100
     AS path: [2222] I 
     Communities: xxxx:xxxx no-export
     Cluster ID: 0.0.0.11         >>>>>>>this part is missing
     Originator ID: x.x.x.x       >>>>>>>this part is missing

as workaround , customer can use "local-as alias" knob. although this knob is targeted other feature but it will allow these attribute propagation