Today I did a 10 mile hike with a downloaded course.
As reported elsewhere, if you start an activity and then select and run your navigation the course fails as it tries to send you back to the start. So the lower information field on the map page gives you distance back to start and continues to increase as you proceed. Obviously too all ETA of next waypoints and end of course are now non-functional.
So I made sure to select/do course before starting activity today. All now good.
Until that is I stopped for lunch and did a Resume Later. When I did resume the activity recorded correctly BUT the navigation tried to send me back to the start. wtf. So annoying.
With the Fenix 3 neither of these were issues (at least in later sw versions). Starting a navigation course after starting an activity would not be a problem and would pick up the course where you where. Similarly, resuming an activity was not a problem for course navigation features.
I will, until Garmin fixes this, not do Resume Later and ensure that I only stop for 15 minutes (when activity autosaves) or perhaps start/stop repeadetedly until I want to set off.
Ho hum.