My Apple Watch no longer can control Homekit accessories vis Siri

I've had my HomeKit lighting and other accessories working well with my Apple watch for months. Today, however, if I ask Siri to, say, turn on certain lights, she responds with "It looks like you haven't set up any HomeKit accessories." I can control the lights via my phone and other devices. Any ideas on how to make Siri on my watch interact with HomeKit again? I did restart the watch already.