No Sound - problem with movies on iTunes for Windows

I can't get the sound on iTunes to work for my movie downloads. I can see the film but there is no audio playback.

I can listen to downloaded music on iTunes, play back a downloaded TV show, so I know it should work. If I open iTunes on my pc which runs on Windows 10, I can play music, watch a TV show or a podcast without any problem. I have the latest version of iTunes (12.12.6.1 as at today, 11/12/2022), all my drivers are up to date, and my speakers work fine.

For example, when the movie start screen opens, I can hear the opening theme, play the extras without any problem but when I play the movie itself, it has no sound.

The movie used to play sound when I first purchased, but not any longer. What am I doing wrong? How can I fix the sound.