Thanks for the scene. LOD was not the problem, but a bug with Distribution->Collisions->Radius, which affects to Edge Mode even if collisions checking is disabled.
I just fixed the bug for the next Forest update.
To fix it in your scene, please do this:
1) Turn on Distribution->Collision, so you can modify the Radius value.
2) Set Radius = 100%
3) Turn off Collisions.
4) Click Display->Update to rebuild the object.