I have had exactly the same issue since going live two weeks ago, spent hours doing pointless resets as asked to by the call centre, none of which have got the channels working and they eventually said give it an hour and it will work.
My subscription is fine as can watch the channels on the BT sport app etc and watch it on my telly via Chromecast but this defeats the object.
And the box gets internet fine as can watch all the catchup apps like iplayer or boxed set on BT players.
Any advice out there?
I have exactly the same problem, BT TV doesn't work as it says i'm not subscribed, also BT sport channels on my youview box don't work.
BT have confirmed i'm subscribed to BT Sport and i'm being charged, the BT Sport works on app and internet but not on the TV.
Is it possible someone can have a look? BT have even said that they can see an issue with the subscription that hasn't gone through properly....