Tracks appear on map as a set of ugly blue triangles?

How did you create the track? Try creating it in Garmin Connect, and see how it looks like then. For example your track may excessively use waypoints instead of course points. Or make the Course public, and post a link to it here.

If remember right it was exported from Basecamp as GPX and Imported in Explorer. I'll make a couple of more tests but so far I don't like how it looks like generally..