Bgp routes in vrf became unreachable when redistribute in bgp-mpls-vpn

I'm peering with an other AS in vrf, and when I tried to redistribute the routes to bgp-vpls-vpn, it became unreachable, look like not doing recursive calculation.

/routing/route> print detail where 172.20.19.81 in dst-address 
Flags: X - disabled, F - filtered, U - unreachable, A - active; 
c - connect, s - static, r - rip, b - bgp, n - bgp-net, o - ospf, i - isis, d - dhcp, v - vpn, m - modem, a - ldp-address, l - ldp-mapping, g - slaac, y - bgp-mpls-vpn, e - evpn; 
H - hw-offloaded; + - ecmp, B - blackhole 

 Ab   afi=ip contribution=active dst-address=172.20.19.64/27 routing-table=dn42 gateway=172.20.19.81@dn42 immediate-gw=172.20.19.81%dn42.routebits distance=20 scope=40 target-scope=30 
       belongs-to="bgp-IP-172.20.19.81@*1" rpki=valid 
       bgp.session=dn42.routebits.v4-1 .aggregator="4242420207:172.20.19.81" .as-path="4242420207" .communities=64511:51 
       .large-communities=4242420207:120:18,4242420207:140:51,4242423077:1:52,4242423077:1:1344 .weight=8000 .med=0 .atomic-aggregate=yes .origin=igp 
       debug.fwp-ptr=0x20444660 

 As   afi=ip contribution=active dst-address=172.20.19.81/32 routing-table=dn42 gateway=dn42.routebits@dn42 immediate-gw=dn42.routebits distance=1 scope=30 target-scope=10 vrf-interface=dn42 
       belongs-to="static" 
       debug.fwp-ptr=0x204421E0 

 Uy   afi=vpnv4 contribution=unreachable dst-address=172.20.19.64/27&65000:4242423077 routing-table=main label=1224 gateway=172.20.19.81@dn42 distance=200 scope=40 target-scope=10 
       belongs-to="dn42-bgp-IP-172.20.19.81@*1-export" 
       bgp.session=dn42.routebits.v4-1 .aggregator="4242420207:172.20.19.81" .as-path="4242420207" .communities=64511:51 .ext-communities=rt:65000:4242423077 
       .large-communities=4242420207:120:18,4242420207:140:51,4242423077:1:52,4242423077:1:1344 .med=0 .origin=igp 
       debug.fwp-ptr=0x20445360 

 Ay   afi=vpnv4 contribution=active dst-address=172.20.19.81/32&65000:4242423077 routing-table=main label=630 gateway=dn42.routebits@dn42 immediate-gw=dn42.routebits distance=200 scope=40 
       target-scope=10 belongs-to="dn42-static-export" 
       bgp.ext-communities=rt:65000:4242423077 .origin=incomplete 
       debug.fwp-ptr=0x20442D80 

likes above, route 1 is active because next_hop is reachable via static route 2, but after bgp-mpls-vpn export, route 3 is unreachable while route 4 is active.

After digging a little deeper, I've found that the problem maybe cause by "target-scope".

/routing/nexthop> print where address~"172.20.19.81"
Flags: R - REACHABLE
Columns: ADDRESS, SCOPE, TARGET-SCOPE, IMMEDIATE-GW.ADDRESS, IMMEDIATE-GW.WEIGHT, IMMEDIATE-GW.FLAP-COUNT, IMMEDIATE-GW.INTERFACE-IDX, IMMEDIATE-GW.MPLS-PEER-ID, IMMEDIATE-GW.MPLS-LABEL, IMMEDIA>
  ADDRESS            SCOPE  TARGET-SCOPE  IMMEDIATE-GW.ADDRESS              IMMEDIATE-GW.WEIGHT  IMMEDIATE-GW.FLAP-COUNT  IM  I  IMMEDIATE-GW.MPLS-LABEL  IMMEDIATE-GW.BLACKHOLE
R 172.20.19.81@dn42     40            30  172.20.19.81%dn42.routebits@dn42                    1               1309757501  17  0               4294967295  no                    
  172.20.19.81@dn42     40            10                                                                                                                                        

route 1's target-scope is 30, but after copyed to route 3, target-scope had been set to 10.

Have you checked 7.21rc3?

7.21rc3 did not fix that.

problem temporary fixed by setting scope=10 target-sope=9 for static routes.