using car template scripts-- car hits invisible wall

Using car template scripts in version 7.85, the car hits an invisible wall and stops on terrain created in MED. It happens in several areas without apparent reason. I have turned on wireframe and see no obstructions.

The world includes a skybox and terrain. The terrain has been scaled up.

I've played around with wheel scale and shape along with a multitude of other settings.

have you set the terrain's POLYGON flag?

Yes, I did. I tried all the collision settings available under properties.
The terrain is scaled up in WED, but I don't know.

It's using the default car settings currently. I thought maybe I had messed with those settings so much that something went crazy so I just took it back to default settings.

Did this ever get resolved? I have the same problem