Directly from the demo program. I added the log line to track if polygon was selected. it never was selected.
B4X:
Private Sub OMaps_PolygonClick (SelectedPolygon As MapPolygon)
ResetObjPanel
LabelType.Text="Polygon"
ObjSelected=SelectedPolygon
Log ("Polygon Click")
wait for (SelectedPolygon.GetPoints) COMPLETE(Points As List)
LabelInfo.Text=$"Points: ${Points.Size}"$
End Sub