Well mine was working fine on my Smart Hub with no issues what so ever, then it came to do its forced automated reboot and when it came back up IPv6 was no longer enabled.
No matter how many time I did a reboot it failed to come back up, brought a new router and IPv6 worked first go, no matter how many time I rebooted it IPv6 was there.
So I thought maybe IPv6 was now working ok so I connected the Smart Hub back and nope no IPv6.
All BT Care have to say about it was they are aware of the issue and that they have no fix date.
I really need to have IPv6 enabled due to I am a software developer and I am currently working on network code which uses IPv6, so I need it at the moment.