I was seeing hair particle systems emit from vertex groups. But, every time now, when I select a vertex group in “Density”, the hairs emit from outside the vertex group. So, I’ve been separating the faces into another object to get the hairs to emit from those vertices.
For a cube, the hairs emit from all faces that are on the same axis. For example, if I select 4 faces in the middle of a cube and create a vertex group, where there is 32 vertices per edge, hairs emit from the entire side of the cube, but not the other sides of the cube. If my mesh is more complex, the hairs emit from the entire mesh.
So, what is causing this? I am using 2.91.2 or 2.92 beta.