When driving this motorway (http://www.openstreetmap.org/way/264484986/history) north, the app shows the lane assistant - 4 lanes. However, the lane on the very right is displayed as slight left instead of slight right, although turn:lanes is tagged as |||slight_right.
Here are the coordinates to test, map Germany West: Start: 51.988; 8.61545 End: 51.99244; 8.61736
What Chattiewoman mentions is an error in Navigator, what PrzemekSupak mentions is an error in OSM and can be easily corrected.
I use this overpass turbo query to check for turn:lanes -> http://overpass-turbo.eu/s/5mN Click "Execute" (top-left) and see for your self. You can search, pan&zoom, and save the query. I have a few others for likewise situations.
Navigator is displaying the case Przemek mentioned, not the one from chattiewoman. Here I would start with the fix of the map. p.s. hvdwolf, thanks for link