Error when navigating

I tried to use navigation for a 15K roundtrip run in a new terrain and encountered the following problem: After about 3k the navigation decided to lead me back to the start. When I saw that navigation simply reversed course, I stopped it and tried to reload it, leading to the same result.

When I am on route and my Fenix looses track it always navigates me back to the start without any noticeable reason, instead of just continuing the route.

I would like to report this behavior as a bug, Any ideas where I can do that?