ipv6 tunnelbroker gif interface in backup node

[GreenMatter]

I don't have native ipv6 WAN so I use tunnelbroker via gif device. Local address (in gif device) is set to WAN carp vip in both nodes. All works well in master node but once backup node is in charge, I can't get packets flowing through ipv6 gateway (based on gif to opt interface). I tried toggling down/up manually gif device, disabling and enabling of respective opt interface, saving once again ipv6 gateway and nothing helps. I have 100% packets loss...
ipv6 opt interface doesn't have carp vip since itself doesn't have any regular ip address.
Am I doing something wrong?