Android Question OSMDroid 6 MapView shows only a grid when returning to a B4XPage from another page

[GeoT]

In B4XMainPage, I have a MapView with two markers created using the OSMDroid 6 library.
Why does the map lose its state when returning from another page, showing only a grid?

Also:

Sub B4XPage_Appear
    Log("mapView1.IsInitialized = " & mapView1.IsInitialized)    ' Gives true
    Log("Overlays count: " & mapView1.Overlays.Size)    ' Gives 0
End Sub

How can I fix this?
How to control the MapView lifecycle or refresh cycle?