DJI CrystalSky, downloaded offline maps present but are not displaying in latest version of DJI Go 4 V4.3.16

[Myha]

I have reviewed the other Post on the Crystalsky offline maps issue, but it does not seem to address the problem that I am seeing.
Crystalsky firmware version 2.6.6.0. When I check for updates, none are shown when wifi is connected.

I have uploaded images demonstrating the problem and describe the process in the following sequence: -

I have updated DJI Go4 to the latest version 4.3.16. See image IMG_8994.JPG .
I have downloaded Offline maps for areas of interest. See image IMG_8991.JPG showing list of maps.
I then turned off my wifi. See image IMG_8987.JPG and image IMG_8990.JPG confirming that I have no wifi.
If I select "Christchurch" from the list offline maps (IMG_8991.JPG ) I am presented with a map of Christchurch. See image IMG_8992.JPG .
If I then enter the main screen of the DJI Go4 App I have a blank screen where the map should be displayed See image IMG_8993.JPG .

If I turn on wifi again then the map in the DJI Go4 App will appear.
If I turn off wifi, power down the Crystalsky, power up the Crystalsky with no wifi connection and then enter DJI Go4 App, no map regardless of zooming in or out is displayed..

Question: What is the point of the downloaded maps as shown in image IMG_8991.JPG? I need to operate without a wifi connection.

I have uninstalled this version of DJI Go4 App several times, and then re-installed it with power down/power up sequences, but this has no effect.

 

[Myha]

Simon Li provided the answer!
Under Battery Saving make sure that the Location Services is ENABLED!