We recently released an update to the BritBox app for AppleTV devices that fixes this issue.
Normally your AppleTV will be set to update your apps automatically, however you can also check and update the BritBox app manually. Here's how:
- Open the App Store on your AppleTV.
- Select the BritBox app.
- Check for an update. If it's available, click 'update'.
- Once the update is complete, the 'update' option will switch to Open.
If you're not able to run the update, make sure your AppleTV's software is up to date, and try deleting and reinstalling the BritBox app.