It's not the specific track, it's a spline glitch that shows up from time to time. If you have a pre-glitch save you can revert to that would be good! If not try 'Save As' (to make a new version of the route) and then merge all layers down to the route layer....
gawpo50 says it's a known issue with that object, apparently some people know what causes a fixed track section to do that. Be nice if they shared the knowledge, especially if there's a way to identify which fixed track objects have the bug so we can avoid using them if there's no easy way to fix them.
For your route, start looking at whatever fixed track you have attached to spline track, one of those is the origin of the bug.