I am having a similar issue with my HomePod and Philips Hue lights.
I recently purchased the Philips Hue White Starter Kit from Apple soon after my HomePod was delivered. I setup the bridge and lights, but all of my Apple devices were having "no response" error messages even when the lights were working as expected. I reset my Hue Bridge and restarted the setup process. After this, I couldn't find the bulbs to pair them again. After multiple power cycles of the bridge, I was able to pair both lights. These lights are installed in my kitchen where the HomePod resides, and they are within 2 feet of each other as pendant lights above my kitchen island. The left bulb had no issues at all. The right bulb would rarely work as expected. It would not turn on with the other light. It would not dim the same amount at times. It wouldn't even work as expected in the Hue app. After talking to multiple friends that love their Hue lights, I was convinced I had a defective bulb. Apple exchanged the entire starter kit for a new starter kit.
The new starter kit setup process was the same as the first time except my HomePod cannot reach the new kit. My iPhone X and Apple Watch Series 2 can both connect with Siri and the Home app to connect and control the lights seamlessly. I reset my HomePod, and it is acting the same as before the reset.
Why is the HomePod having issues while my other devices are fine? I have other smart devices that still work fine with the HomePod (ecobee 3 lite thermostat, iHome iSP6 SmartPlug, iHome iSP100 Outdoor SmartPlug). I have two Apple TV 4th Generation models that have been setup as Home hubs. The Living Room Apple TV is currently set as the Home hub. The Kitchen HomePod and Bedroom Apple TV are showing a "Standby" status in the Hub section of the Home app on my iPhone.