Just to follow this up. I of course couldn’t export the geometry from Maya without creating a very complex collider to go with it.
Instead, at least just as a test, I started laying down colliders to walk on, on my landscape. This is working, it’s not a great solution as i would have to do this everywhere, but again points at the landscape as being a problem and I’m not exactly sure why. Again, while walking on the landscape the game is not sure where I am, and thus starts culling things randomly, flashing on and off. If I jumped things would go on, and on placed colliders it seems to work.
I still have to find a better solution but it points in the right direction. I built landscape in another level from the same maps, and that is not doing this at all. It is a far less complex scene, but i’m going to look at other variables that could be the difference in one working and the other not… my suspect right now is scale, but I’m not sure about that.