Quick update - I've sorted the physics (I think)

Thankfully this will be a much shorter post.

So I've gone through all of the track parts that are made up of square and cube shapes, and have replaced all of the mesh colliders with primitive 'box' colliders.

So far the "Invisible Wall" issue hasn't reared it's ugly head once...

I've uploaded a new build to reflect this.

Sorry for the delay between post... I've become addicted to playing Ark, again... :(