I recently decided to use my iPad
Air 2 & installed Go4, and like a lot of us, couldn’t see any maps. Having read loads of threads on this subject, I was ‘messing’ about with the map window when I noticed that it had defaulted to zoomed in at a scale of about 5 metres. I pinched out, & out until eventually... Africa came into view - I was in the middle of the Atlantic! Not many roads out there!
I dragged the map to my location in the UK, zoomed in, and yey, the map detail appeared & I think it has downloaded to the cache.