MapboxVisionAR not show video or lines on the screen

Nobody has claimed this yet.

## Description
I have use example code given here https://github.com/mapbox/mapbox-vision-ios/blob/master/Examples/VisionExamples/Examples/ARNavigationViewController.swift , but when i run this on device, it shows only blank screen with mapbox logo on it. No video and no route lines etc shown.
I am using access token as mentioned in integration guide. When camera permission is asked i also authorize to it.

## Goal
Goal is to show the AR Navigation as they described for demo.

## Steps
- created account and add secret key in .netrc file
- Integrated through cocoa pods
- added code from example https://github.com/mapbox/mapbox-vision-ios/blob/master/Examples/VisionExamples/Examples/ARNavigationViewController.swift
- Run on the device,
- Origion is set my current location lat, lng
- Destination is set an other point to some distance my current location
- Route is obtained and print in console
- But no video and no line of route draw on screen
- [https://ibb.co/NT5dX9Y](https://ibb.co/NT5dX9Y)

Start with Examples/VisionExamples/Examples/ARNavigationViewController.swift and reproduce the reported device flow using the integration and permissions described in the issue. Trace why the camera video and route lines are absent despite a route being obtained; done means the AR Navigation demo displays video and the route overlay instead of a blank screen.

Written by the indexing model from the issue text.