Google Maps location not working when offline

You may want to try an alternative to Google Maps : OsmAnd (https://osmand.net/). It's a navigation app with downloadable maps for offline use.

Also, be aware that Android considers two types of "location" :

• "Precise location" (about 1-10m) is got from satellites (american GPS, russian GLONASS, chinese Beidou, and soon european Galileo, according to your device). You'll need a clear view of the sky and up to 15 minutes to get a good position fix.
• "Coarse location" (about 100m-1km, enough to know what city you're in) tries to get your location by scanning your surrounding cell antennas and wifi/Bluetooth access points, sending the list to Google's servers, which will then give back an estimate of your position (I bet you didn't know about that spying...). Alternative backends exist that mimick that behaviour, but without relying on Google. Check MicroG's Unified NLP if you're interested (https://github.com/microg/android_packages_apps_UnifiedNlp/blob/master/README.md).

A good app to check your precise and coarse locations is SatStat (https://github.com/mvglasow/satstat) : on the map view, red is precise, and blue is coarse location.

There is actually a Google Maps Offline version app you can download. I always had problems getting directions with google maps on devices that didn't have cellular connections, I now use one of my old smartphones as a dedicated GPS for my car.