Audio description on BritBox

Hi folks. So, I’ve come to start watching Downton Abbey on BritBox only to discover that despite the fact it has audio description which I can access on both my iPhone and iPad, I cannot get audio description using the BritBox app on Apple TV.

I do not have the latest Apple TV, but the version that was released in 2020, which I believe is 4K, but I might be wrong. Either way, all apps are up-to-date as is the operating system. Apparently, if you start playing an eppisode of a series that has audio description, you should then be able to start audio description if it is available. True on the iPad and iPhone, but not the TV app. Audio description is switched on in settings and accessibility as well. If anyone is using the BritBox app on Apple TV, are you having the same challenge? Thanks.