I have a mesh that I have not created myself. I took an existing mesh and started modifying it for my own purposes. Suddenly I notice some vertices go crazy when I move (or grab) certain vertices.
This is NOT due to proportional editing as far as I can tell (hopefully you can tell as well from the gif).
I don't know how I got these vertices into that state, I have been removing edges, filling gaps with new faces etc on the mesh, and now this. Any idea how I can repair that state? From the image it appears to happen when vertex is moved, but it happens as soon as G is pressed if I do that instead.
Here's an image of some of the settings. You can see x-mirror and topology mirror is on. It seems it's the topology mirror that causes it, removing it stops the weird behaviour. And I don't need it and it doesn't make sense for this mesh, so my problem is solved for me. Maybe others have the same problem.