For some reason, the following request just returned with 0 results.

https://api.themoviedb.org/3/watch/providers/movie?language=en&watch_region=GB&api_key=[API_KEY]

But if I change GB (Great Britain) to DE (Germany):

https://api.themoviedb.org/3/watch/providers/movie?language=en&watch_region=DE&api_key=[API_KEY]

it works fine, returning 118 channels.

Similarly it also works fine for FR (France):

https://api.themoviedb.org/3/watch/providers/movie?language=en&watch_region=FR&api_key=[API_KEY]

What is the recommended way to find all channels in Great Britain?

Thanks.