At different zoom levels there is different rendering of the road. On some (less detail) zoom levels the road is shown completely and at some higher zoom levels different portions of the road are missing. What could be the problem? I’m using iD in browser editor if that is making the difference…
It is normal for tiles at different zoom levels to be updated on different schedules, so where there have been recent changes things can look out of sync. In particular low (less detailed) zoom levels generally update less frequently.
It is also possible you have old tiles in your own local cache so worth clearing your cache just in case. The track looks OK to me from level 13 to 19. It doesn’t appear yet at level 12 and lower but it would be barely visible at that level anyway.