Do you have WiFi "off"? I like to leave WiFi "off" because I prefer to use fast wired ethernet. However more and more Apple requires WiFi for some of its functions (AirDrop for one). I turned WiFi back "on" and the widget displayed my location and weather. Apparently something in Location Services requires WiFi... Anyway, try that. Dumb workaround if you are on a Mac that stays in one place all the time, and you don't want WiFi on all the time: manually add your location, turn off Wifi, and...it works. 🤪