Found a bug in iTunes when played via Apple TV 4K tvOS 13.
Multichannel (surround sound) will not work for the English (non AD (non commentary)) audio track iTunes version of a Pirates of the Caribbean: Curse of the Black Pearl if played via an Apple TV 4K tvOS 13.
Any other audio option works fine for multichannel surround (French, Spanish & English AD (commentary version)) — But the iTunes English only (without commentary) will not send the correct audio encoding for multichannel surround for that movie. Probably some other movies too, but I know that one for sure has this bug and its only iTunes.. all other streaming services, no problem at all with multichannel surround. Did all the due diligence and narrowed it to that audio track on that movie on itunes only.