I'm having this same problem. I was able to access Britbox just fine in September, which I think was the last time I tried to watch anything on the channel. When I tried to bring it up earlier this week, however, it loaded the top menu, hung there for several seconds without responding to my remote, then dropped back to my TV's home screen. None of my other streaming channels have this issue. I have already updated everything, and tried deleting the channel, rebooting my system, and re-adding the channel multiple times.
Britbox has a huge problem on their hands. I'll give them a week.
