I've been having the same issue. After talking to Apple Support on the phone, I had reset my HomePod, restarted my cable modem/router, ensured my iPads and MacBook Pro could still find their location on the Maps app, but still the HomePod didn't know its location. The Apple Support person then put me on hold for a few minutes. When she came back, she had me go into the Home app on my iPhone, press on the HomePod icon on the screen, press the "Details" button, then go down to Location Services and turn it off for 10 seconds. Once I turned it back on, my HomePod was able to give me the current temperature and weather. Yay!