Why won’t Siri turn on lights in rooms I specify?

For the past few years, Siri and Home have worked flawlessly when issuing commands such as “Siri, turn on the living room lights”. That is, up until about a week ago when Siri suddenly started asking “Which room” and presenting me with a list of rooms. If I say “living room”, she would just ask “Which room?” again. I inevitably have to turn the lights (or accessories) on manually. How can I use Siri to control lights as before?

I’m running iOS 17.5.1 on iPhone 13 Pro Max; unsure of Home app version, but it updated yesterday.

Thanks, in advance, for any help and suggestions!

Chris