Amazon prime titles won't play english audio (Something went wrong)

When I try to play movies on Amazon Prime, particularly older titles from MGM, they often start off with Italian, Portuguese or Spanish audio. When I try to switch to English (original) audio I always get the dreaded "Something went wrong". I can switch to all other languages, but never back to English.

I never have these problems with any other media app, or with more recent titles on Prime.

The Primevideo app works perfectly on my iPhone and iPad. This only happens on AppleTV.

I have tried all the suggestions that I've found regarding "Something went wrong" in other cases, reboots, reinstalls, disconnecting power plug, manual DNS and so on.

I have gen 3 of Apple TV (no 4k) but never the less I even tried changing resolution (as described as a problem solver for gen 4 devices) without success.

Any ideas anyone?