Having created a 'route' with just one waypoint in the navigation app, if select the route and click 'Navigate' imediatly the route planning fails. If you wait (about 15 seconds) for your current location to register then click navigate it plots the route fine (mostly).
On further testing the route often fails to calculate. When this happens the only visible solution is to return to the routes list and try again as it this point there is no 'Navigate' button.
I have though discovered that rotating the phone to landscape causes the route to be recalculated. and the navigate arrow button to be displayed.
Thank you for making this suggestion and sharing your findings.
I have added this suggestion to the list for the developers to have a look at.
I will now be closing the thread to prevent other users from sharing other suggestions not related to this one in here.
Customer Support MyRoute-app.