Phasing Through Terrain in 4.7.2

I decided to start learning how to mess with Terrain in UE4 with the latest update, and everything was going fine. I closed out and returned today to find that my ball character was phasing through most of the level geometry. By running the erosion tool over the geometry (updating it, in a sense) it started working, but as soon as I launched the project, or saved, quit, and reloaded, the phasing problem returned. I have no idea what’s going wrong; here’s a gif of the terrain working in editor and not working when launched:

://gfycat/VagueGoodGrouse

Any help would be much appreciated.

-make sure that you quality settings are on epic
-check the collision thickness of your terrain :slight_smile:

Figured out the problem, kind of: I had tried to use the visibility tool which meant some of the terrain was “invisible,” meaning I could pass through it. However, the terrain was still visible. I can’t make the visibility tool work correctly; it either makes me able to phase through visible terrain and/or makes the material from that quadrant of the terrain vanish, replacing it with the World Grid. Any ideas?