Siri no longer turns on subtitles

For years of Apple TV use I have had Siri turn subtitles on and off when desired. Lately nothing happens when I ask Siri to do that. However, I am able to turn the subtitles off and on by pressing downward on the control ring and moving right to a subtitles icon. This does work, but is less convenient.

What happened? Did a recent software update cause this, or have I somehow inadvertently changed a setting?

I am using the latest version of Apple TV and software is up to date.