IPv6 masqurade / nat not working inside container


currently i have a problem with IPv6 nat inside a container. I have setup a tun device via ssh and masqurade ipv6 via ip6tables. But it does not work. I have tried the same with ipv4 and iptables and it works. I have tried the same (IPv6) on the parant host and it works. Is there a block from lxc/lxd site ?