Hey guys, try this and test 'er out. Seemed like it worked for me.
Credit goes to @ Lopuska from his PhysicsGMKRefactor work, and Az and Timmy for remembering about it
For those asking,
But really, should the physics version really matter? I'd imagine the terrain system would be programmed to recognize when a part of its surface has been set to "empty", regardless.
The setup passes through the physics abstraction layer on to the physics library in question. The issue was that the abstraction part didn't properly translate the holes in such a way for bullet to know about all that. the stock and physx stuff happened to. The above code change should make bullet properly aware of holes in the terrain, so give it a shot and let me know