Been using Blender for years, but for some reason in this project I'm working on I can't use the knife tool. Its all low poly stuff and I've used the knife tool in the project since I started it. At any rate, when I hit the K key, the knife tool comes up but it has no effect on any of the meshes. I see, what looks like a new vertice at 0,0,0 but the icon wont snap to anything. I checked it in a clean project and it has no issues. I tried different meshes in the same project to no avail. There are no double faces and the normals are not flipped. Any ideas?