IPv6 link-local duplicate bring the ipv6 traffic on POS interface
Issue : ipv6 route not installed , interface up  , ipv6 protocol down.
Image : IOS XR 4.2.4 - GSR12810
show ipv6 interface brief
Image : IOS XR 4.2.4 - GSR12810
show ipv6 interface brief
 
#show ipv6 interface brief
POS0/2/0/1             [Up/Down]
    fe80::387c:dfff:fee6:b908                     
    2001:x:x:x::1e       
But interface is up /up show int POS0/2/0/1 POS0/2/0/1 is up, line protocol is up (APS not Configured )if you check the ipv6 interface its reveals hence the interface deteced duplicate link local its brings down the ipv6 protocol.
#show ipv6 interface pos 0/2/0/1
 [KPOS0/2/0/1 is Up, ipv6 protocol is Down, Vrfid is default (0x60000000)
  IPv6 is down (link local duplicate), link-local address is fe80::387c:dfff:fee6:b908 [DUPLICATE]
  Global unicast address(es):
    2001:x:x:xx::1e, subnet is 2001:x:x:x::1c/126 [TENTATIVE]
  Joined group address(es): ff02::1:ffe6:b908 ff02::2 ff02::1
Quite strange issue , can related to multiple bug ids : 
CSCtq57619,
CSCeh47611 and
CSCtq55280
i've resolved issue after manually binding the link local address but i think following will do : 
clear ipv6 duplicate addresses
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