Massive Collision Spikes on Landscape

I noticed when trying to drag a static mesh onto my landscape, it wouldn’t snap to the ground, but would change its xyz randomly as I dragged it. When running the game, my player falls through the landscape randomly. I checked collision view, and random components in my landscape have thousands of vertical collision spikes from lower to upper bounds.

I’ve been working on this project for a while and have never had an issue like this. The only thing I’ve done on my save since it broke was change LOD parameters for a static mesh. I’ve rebuilt everything and restarted the editor but nothing has worked. Has anyone fixed this before?