Why does the cars fall through the terrain??

As you can see in the video the car just falls through the terrain instead of colliding. Why? Please help me out.
(I added a second terrain for the background but I removed it...)

 

I have deleted the terrain and have re-launched the game many times, still won't work

 

Clearing cache could work..? Or is that only for textures? I dunno.

 

Yes.

 

Editor is bit broken here too, I have had this happen to me and way to fix this was to edit all .json files in map folder to contain only one intended terrain as editor kinda is not deleting those lines of other terrain, happens sometimes, also one terrain is probably in levels/ instead of levels/yourmap

That is some odd bug, among many in the editor, lines in files are not being updated.

 

What exactly should I change?
--- Post updated ---
Please reply, I need to get this fixed within an hour

 

You need to examine all of the files for mentioning of .ter and then compare them to see which contains line of terrain that should not be there anymore. There is lot of files where terrain files are referenced on, in main folder there are several items.level.json files too which all you need to examine.

 

I have now examined every damn folder and files, but still doesn't work! Could it be anything else?