I have a iPad-mini wifi only device. Several times I have been able to pull up a map that I have bookmarked without being connected to the internet. This has been when I was in a vehicle with no cellular,data plan, ect. available. Lately this has not worked. I have location services turned on. Why can I pull up the maps sometimes but not always?
Make sure you enable WiFi all the time. Even if you don’t have cellular data or connected to Internet, the device can still estimate your location based on the surrounding WiFi source.
Update: Maps will use the surrounding WiFi (protected or not) to pinpoint your position. That might explain why it only occasionally works. If your iPad can’t find any WiFi available, then your position can’t be estimated.