Connection inside of a spline. SC can't follow.

[Trainzland]

It seems if you have a connection inside of a spline then the SC can't follow against the spline direction. (red arrow)
The blue line represent the possible moving direction of the SplineController.




The only way to build a working connection is to use Split on Spline 3 at the red arrow.
But Split deletes the last ControlPoint of Spline3 unfortunately.



So I recommended to have a Split function that doesn't delete the ControlPoint of the un-parted spline.
It's a lot of word to recombine the un-parted spline and fix the connection because the Connection position is always lost too.

But anyway if these 3 single splines are connected, the connection itself on snyc dir/len/rot gets corrupted unfortunately.
The reason is snyc length. If its activated it seems the function doesn't take care about math.sign of the handles.

[Jake]

SplineControllers don't follow connections, event handlers do by setting the controller to a new spline. So I need at least the code of the event handler you're using. Connection settings would be of help as well.

[Trainzland]

SplineControllers don't follow connections, event handlers do by setting the controller to a new spline. So I need at least the code of the event handler you're using. Connection settings would be of help as well.

The Connection settings prevent to set the FollowUp (or Heading however) into the red arrow direction. See image below.
Your new Event Handler (UseFollowUp) you provided works in this case. But crash again in other situations unfortunately.

Anyway..
This situations while curvy produce bugs (mostly while editing Connections) and cause unity to fail are complex. Explaining the complex stuff seems  waste of time currently,
because it there is none who's willing or interesting to understand this complex fails. Laying a simple spline from A to B works. Working with Connections produce too much fails to get in basic workflow. I would recommended to spend more time into the editing Connection features to keep them running better.

[Jake]

Yes, thery're complex, and trying to reproduce a problem from a set of images is next to impossible. A simple repro scene (saved scene file is sufficient if there's no custom code in it) sometimes does more than thousand words.