‘The map does not generated for the 5 last degrees’
I guess you use the mobile app if your polar expedition is far beyond 85°S. With the mobile app, you have only the map using the Mercator projection available and this type of projection cannot show high latitude regions. On Windy website, the 3D rendering offers almost total coverage of the polar regions.
Concerning time, near Longitude -90° (90°W), as shown with this screenshot, the local time is UTC-6h. It seems to be correct ?
Could you tell us which device you are using during these expeditions and how you get the internet connection via satellite?