I took a look at the route for you, and I can't find any "invisible" track. All of the track renders properly as far as I can tell when I followed the line across the route.
Is there any particular part of the route that's causing this for you?
Can you provide the KUID of the track that's causing the problem?
You can get the KUID of the track by enabling show KUIDs in Surveyor in the menu within Trainz. click on settings located under the 3-bar menu, click on General Settings then click on Show object/track/train KUIDS in Surveyor.
In Surveyor, click on the track pull out and then click on the track in question. This will display the KUID lower right corner of the screen.
Now with that said, there have been some issues with track taking a bit of time to render for some people including myself. Sometimes, if you wait a minute the splines, including roads and tracks will eventually draw in.