@Rag31. Hi. Britbox accounts are NOT interchangeable. How did you subscribe/ who are you paying for it ? Prime and "therokuCHANNEL" work as 3rd party hosts that sell Britbox subscriptions. These are different than a stand alone Britbox subscription (direct from Britbox website), which can be watched on the stand alone Britbox app via a Roku DEVICE. If you subscribed thru Prime, then you must access it thru Prime & find your subscriptions or their internal Hub for Britbox. These are all separate accounts & you cant sign in the other ways.
I have the same exact issue as the main poster. I tried everything like they did. I cannot get into the login screen at all on Britbox. I am so frustrated this needs to be fixed asap.
@Hisbeauty4ashes. See if you can sign in on Britbox website or Android App ? Somehow my sign in worked itself out after many reboots. I still can't view all the shows I've saved to my "Watchlist". It got totally screwed up & seems like Roku doesn't care.
For what its worth, when I subscribe to Britbox, I do it through Prime.
I subscribed directly with Britbox one time because of a special low annual price subscription offer, but I found the Britbox channel/app to be slow and often buggy on my devices. (no trouble with sign-ins though).
While I really don't care for Prime Video, Britbox does work flawlessly through it.