After reading several threads it seems like there are a few people that has issue getting the map on their Vision app.
Try these instructions step by step to pre-load / cache your map:
1. Power off WiFi Extender, Controller, and P2V or P2V+
2. On your device with Vision app, connect to mobile network and / or Wifi.
3. Verify your network connection by checking Facebook or Email.
4. Once you verify that you have network connectivity. Open up Vision App.
5. Click on "Camera" icon.
6. Left swip to get into Ground Station / Way Point
7. On upper right hand corner, select the overlay / map you want. I prefer Hybrid map.
8. Move the map to area where you want fly.
9. Zoom in maximum possible.
10. Move map to view all area where you will want to set waypoint.
Done.
Step 10 is where the Vision App will cache all the map you've viewed so when you are connected to your P2V/P2V+ again without internet connection, the map will show up.
Hope this works for you.