Siri on one HomePod can’t find HomeKit devices

I have an expansive HomeKit Network with multiple AppleTVs and HomePods with lots of HomeKit devices from Eve, Kokeek as well as a HomeBridge that connects through to Control4 with multiple lights, curtains and air conditioners. Yes it’s been challenging but I had Siri working with voice control from my watch, iphone, iPad and any HomePod in earshot. However one HomePod in the Bedroom has lost the plot. A command - “Hey Siri, Bedroom curtains open” was working fine. Now she responds with I cannot find that device, Blah, Blah Blah........ however the same Voice command works fine from My Apple Watch as does the button in HomeKit App. The other HomePod in another room works fine. I have restarted the delinquent HomePod, but Siri on that device has suddenly become stupid! Any ideas??