Sculpted Project Terrain Loads Flat

Hi all,

I am restarting work on a project from a few months ago, which has a single test scene at the moment with two pieces of terrain making up the playable area. When I load the editor the terrain loads as flat, however all brushed on tress & bushes, all objects (scenic or player) collide as if the terrain is the sculpted shape it should be.

The result is some flat terrain below every other object that is hovering, but collides as if the terrain was sculpted the way it should be.

Has this happened before? Is it a known issue? Is there a fix/work around?

Any & all help is appreciated.

An image of your scene would help a lot. Trying to visualize this is a bit hard.